You're sending these girls mixed messages and they're getting freaked out.
Now, don't get me wrong, i'm all for escalating super quickly and getting physical fast. HOWEVER, you have to keep in mind what your intentions are.
There are 3 branches in the road (normally), when you're figuring out what you want to do with her:
1) Friends w/ Benefits/ F-Buddies - This is pretty self-explanatory. From what I can gather, this is normally what you go for. Escalating super fast, meeting the girl at a bar/club and then taking her home that night, etc. THESE ARENT THE GIRLS YOU WANT TO GET IN LTR's WITH. In general. Think about it. If you banged some chick in the club within hours of meeting her, do you really trust her enough to become exclusive? Not to mention, is she usually high enough quality?
2) Dating/LTR - Yes, you should still be having sex quickly with these girls. However, with the quality ones, you're more interested in dating, i typically prefer it if the girl makes me wait at LEAST until the 2nd/3rd time I hang with her before she gives it up.
3) Friends - You may say "why would i purposely get in the friendzone??". For a couple reasons: A) to expand your social circle and hook up with her hot girl friends. B) You enjoy hanging with her but arent sexually attracted to her.
I think you're mixing up 1 and 2 (at least in the case of the few girls you fall for). You're escalating SUPER quick and banging these girls and sleeping with them, basically telling her girl brain that you're more or less only interested in a physical relationship....and then you go and get all mushy and needy on her. She's thinking 'WTF? This isnt what i signed up for!'. You being good at escalating and getting that lay is not congruent with your personality once you start "falling" for her, and she picks up on it like BOOM.
Essentially, what i think you're doing is skipping the Comfort phase if we're talking about a Attraction/Comfort/Seduction model. I think you're going right for the gold without trying to form any type of connection with the girl, and then when you start to "assume" this connection after hanging out with her a bunch of times, she picks up on the fact that you're not congruent.
Once you get the lay, it hasn't even started if your goal is to keep seeing her. Do NOT put yourself all out on the table right away. Just because you scored a touchdown DOES NOT mean the game is over...far from it. You need to continue to be a mystery to her. Continue to NOT text her back right away and constantly ask what she's doing.
Speaking of text game, i would say to work on that a lot (you said messanger, so i wasnt sure if it's text or Fbook or whatever, but the same general rules apply). Not only are you conveying neediness, but your texts aren't terribly playful and entertaining.
While i'm not a hhuuuge fan of stupid little rules...i think they CAN be helpful as crutches until you get the proper mindset to just carry them out without thinking. Heres a couple points for texting:
a) Take AT LEAST as long to text her back as she took to answer you. Personally, i lean more towards TWICE as long as it took her to get back to you last time.
b) Try to always make her send the last message at the end of the conversation. Dont be the guy who keeps saying "bye" after the convo already ended. just stop responding.
c) Never send 2 messages in a row unless she has been doing that already
d) Its OKAY to text her quickly if you guys have momentum and shes replying to you REALLY quickly. Match her rhythm and mirror it back. HOWEVER, throw in random moments where you just dont respond to her for like a half hour or a few hours and make her wonder. You know that feeling when you like a girl and you get a bit worried when it's been like 2 hours since they got back to you? GIRLS FEEL THE SAME THING. Make her feel that. It WILL keep her attraction up if she can sense you;re not hanging on eveery word.
e) CUT IT OUT with the emoticons and smiley faces and X's and O's. That's girly sh!t. As far as i'm concerned, the ONLY ones you should be using on a regular basis are the winky face (when you're being sexual or playful) or the tongue one (for when you're being playful, but less sexual, or when you make a tongue in cheek or sarcastic ****y/funny remark). I would avoid the "haha's" and the "lol's. Dude. Dont use X's and O's. Ever. Be a man, use regular words and proper grammar.
f) Dont always be the one to initiate contact. I mean a man texts her when he wants, dont get me wrong...but its good to simply wait. If her interest is high enough, she WILL start texting you. Usually.
Fake it till you make it. Ideally you should be keeping yourself busy enough and have enough plates spinning to where these rules NATURALLY happen...but until then, try to change your behavior by implementing them
I've run into this problem a ton in the DJ/Pickup/PUA community. We see getting laid as the end-goal. People have no idea how to maintain attraction for more than a few months with this mindset. They've been striving for the pvssy so much and dont stop to focus on actually IMPROVING their skillset with women. Any moron who approaches dozens of girls a week is going to "get lucky" eventually. It takes a true, skilled, confident, quality man to be able to approach girls, and CONSISTENTLY both get them attracted and KEEP them attracted. Most of these "PUA's" are cringe-inducing in terms of their abilities to maintain a LTR or even MLTR's.
I have the opposite problem. While I can approach well if i'm having a good day/night , I am pretty introverted so i'm very inconsistent in my initial approaches and setting up dates. However, i have my long term game worked out to where once I escalate with a girl and start hanging out consistently, I bring A LOT to the table. Not only this, but i dont put it all out on the table so i leave her constantly guessing. My last girlfriend actually told me that she was super interested in me because she thought i was mysterious and she felt like she was peeling away layers of the onion to find out what i was all about.
I know it's hard once you start having feelings for the girl. I can recommend 2 things: 1) Spinning Plates and 2) Experience.
1) Spinning plates. Self explanatory. if you have more than one girl interested, you wont completely bank on a single girl and she will be able to smell it on you that you have options.
2) Experience. While many guys on here get laid a lot, i question how many of them have actually been in a good LTR and have the skillls to go along with maintaining that LTR and keeping it fun.
LTR?! I know, it's blasphemy! Settling down with JUST ONE GIRL?! It has its benefits. Perhaps the greatest benefit of all is developing the skillset necessary to deal with girls in the long term, keep them interested, keep them attracted, etc. Maintaining a relationship as a Don Juan takes a COMPLETELY DIFFERENT skill set from attracting and banging women initially. The same general principals apply, but the execution and mindset is very different.
You mention that you get worried about them "cheating or dating others". This should not cross your mind. This should not even cross your mind in a committed, long-term relationship, let alone if you two are JUST sleeping together. Because that's what you're doing. Even if you're "dating" and hanging out...YOU'RE BOTH SINGLE. If she wants to suck every guy's **** on the block, that's her prerogative, just as it's yours to bang as many girls as you want when you're single. Do not waste your time worrying about who else she's talking to. You should be concerned about the other 3 girls you're talking to. Even in a LTR, don't be the guy who worries about her cheating. She will sense this. It's a self-fulfilling prophecy.
The guy that is worried about getting cheated on is the EXACT GUY that will USUALLY GET CHEATED ON. The DJ knows that he is of such high quality that it is HER LOSS if she fvcks everything up by cheating on you. GOOD FOR YOU. It's GOOD if she cheats, because not only are you single again, you also weeded out a low quality cheating girl that you are no longer wasting your time with.
Sorry if i just rambled on. It's late and i'm bored, but i hope this helped. Go Get em tiger.