Alright, there's a lot to unpack here so I'm just going to respond to the OP and the fact that you mention being underweight and over 6ft. Looks like plenty of other members are offering sound advice, so I'll offer mine as well.
Same reason I came, cold approaching is my bread and butter so let's see what issues you're having.
Cold approaching should not take a toll on your soul. It is a quick pain; you approach, get rejected, and move on. There should not be much afterthought beyond what you did wrong at that moment and what you could've done better. I believe the pain of rejection is much less than the pain of settling to be with someone less than you desire.
I can't speak for your "friend", but if the last thing he told you was that he thinks you're an autist I don't know whether I'd consider that a friend (unless he's saying this to help you somehow).
That said, you should describe HOW you're approaching these women and with what frequency. You should not be doing it so much in one place at one time that you're being asked to leave. I have never once in my life been asked to leave or even been asked to stop approaching women in any particular place, so the fact that you are means you are doing something fundamentally wrong.
The last girl you approached was more than 2 months ago? That's nothing, dude. If you want success you need way more "at bats" than that. You got a fake number? Who cares? I'm sure a majority of this forum has had that happen at least once to them - it's certainly happened to me before.
This shows a few things wrong with your approach though.
First, you're approaching a store employee. She HAS to be there, she doesn't get to choose whether to accept your interaction. In all likelihood, she's getting paid close to minimum wage and just wants to go home - she does not want to be hit on by strangers. I have a FWB who works the front desk at a gym. She gets hit on CONSTANTLY, and hates it. But she has to be nice to every person who walks in thinking they're the first person to drop a line on her.
Second, you're having a whole conversation without this girl's input; "Hey, I think you're cute, can I have your number?" You don't know her name, her only response is either "yes" or "no", and there's zero reason for her to be interested in you besides your physical appearance in that moment. Have a conversation, see how she reacts, listen to whether she continues the conversation without you having to force it, etc.
And obviously, don't do this with service workers. There are plenty of posts on this forum of guys surprised their barista wasn't interested in them despite "flirting" the whole time as if that's not literally their job.
Change this mentality.
You are not entitled to anything. Dating is a free market where the most desirable men get picked and the least desirable ones do not. There are plenty of posts of guys here thinking that because they had some minor success in the past it should translate to success now and in the future - and they are wrong.
Consider for a moment, if you were a hot girl, would you want to f*** you? If the answer is no, change that.
Dating apps should be used as a supplementary tool at best. Even if you're Chad Thundercoq you're not getting many hot matches because there are simply so few on there. A majority of what you'll swipe on are 5s and 6s who think they deserve a 10. That is not ALWAYS the case, as some of my most consistent FWBs have been from dating apps - but you are competing with a LOT of men.
If a girl is hot on a dating app, every right swipe is a match. I've seen it, my ex showed me. Expect nothing and sometimes be pleasantly surprised, but don't lean on it for your dating life.
That being said, if you're as broke as you say, don't focus too much on this. Get a job, save some money, and maybe go to some local bar on the weekend and see if there's anybody you want to meet there. You should not have to spend a lot of money to meet women.
Personally, I live at home with my parents, am underemployed, and make around $40k/year. I can still make it work and get laid a lot because the other parts of the product, that is me, are quite attractive. You've mentioned before that you're over 6ft. That's very good. Now start going to the gym.
I made a thread not long ago called "Tired of being Fat & Ugly?" about a beginner gym program. Go find and read through that if you need a place to start and have no clue whatsoever.
Otherwise, this whole process is going to take time and you'll fail a lot. You just have to decide whether a bunch of little failures is less painful than a single massive one that lasts your whole life. For me it was.
