Well dude, a couple pieces of advice real quick.
1. If you like someone, don’t play games (i.e. testing them to see if they’ll make a move before you). If you’re enjoying their company, say so. You don’t have to be overbearing or claim that you want to marry them (in fact, if you do feel that way, hold off for awhile before you tell them. What you’re experiencing is just the fleeting feeling of infatuation. It’s powerful, but it’s not real). But you can let them know that you like being around them, and talking to them. The word “creep” gets thrown around way too much these days, and it forces boys to withhold feelings — maybe more than they should. However, there’s no shame in telling someone that you like them.
2. Whether she was interested or not should have no effect on your self-esteem at all. I can’t say for sure either way, because I don’t know her or the details of the situation, but I can tell you this: you’re gonna meet some people in this life who like you, and some who don’t. You may not be able to explain why some people dislike you, and that doesn’t matter. It’s not your job to please them. Stay true to yourself. It’s the only path to happiness.
I have one more timeless piece of advice that you may or may not have already heard, but it’s particularly relevant to your current situation. Carry this advice with you for the rest of your journey of finding love:
If you love something, let it go. If it comes back to you, it’s yours. If it doesn’t, it was never yours to begin with.