Props on grabbing the bull by the horns and going after this area of your life; it will pay off big time.
I have friends who are in their late 20's who STILL won't even ATTEMPT to cold approach because they're so scared of rejection.
As far as feedback, you need to improve your approaches.
For an opener try to talk about something going on around the two of you; esp on a college campus there is always something.
Secondly you need to get out of the sounding like your giving them a interview. All your approaches sound a little robotic (what's your name, what's your major). That's boring vanilla stuff and to be honest it doesn't matter at all. Think of your questions as currency, ask (spend) them wisely.
When you asked the girl if she was stalking you, that was good. Showed her you don't take things too seriously, were fun and if you noticed is the conversation that flowed the best.
If you mimic the care free conversation style you had with that girl things will go better.
And don't be so focused on getting a girl's #; that doesn't really mean much. If you are having a great conversation, try and get the girl to go somewhere with you right there. For instance, if things were going well with that chick you saw at the gym, try and get her to go get something to eat with you if you guys are leaving around the same time etc.
What your going to notice is when you call these girls, they will likely flake out on you or not answer or respond to your
text because you haven't created attraction; you've simply interviewed them.
Change that and your results will improve dramatically.
PIMP