You know, dear fellow, you sound like a nice guy. I realize you said that you are told these nice things about you often, but the biggest thing that I'm noticing through reading your posts, is you don't seem to believe it. Believing it... and REALLY focusing on 'knowing it', will help you immensely. It's really the power of your mind. You just need to resolve to believe the things that you are told. I think more importantly you should do an exercise:
Look in the mirror. Ask yourself: "Am I good looking?" Sure, we can all pick apart the little details that we don't particularly like, but that's counter productive becaue as yo uknow when your close the woman you like, you're not even noticing her zit or her dry skin - you're noticing all of her. So - back to the mirror. "Are you good looking?" - Yes? Ok. Good - now say it "I _____ ______ am good looking." Now that ones done. File it away. One down....
Next: "Am I funny?" .... So you're getting my point. If you find that you are stopping on any of these questions and going "Ohh I'm so STUPID" or "Ohh look how gross my big nose is" .. well you're going to have to spend time getting over that becasue the fact is, people pick up on the things you don't like. I don't mean that this chick is going to start noticing your "big nose", but what she will notice is that you don't particularly feel comfortable with yourself.
When you're on that date and your nervous and your trying to feel out every little detail of the person your with to see if they are giving you any signs that you should lean in to the kiss... Well we're very heightened during these times, so believe me - if you are feeling inadequate, she'll know.
You're 19, so don't act desperate. I know you want a gal and you want to love and that's wonderful! Just don't spend your time feeling like life has already passed you by - you have a ton of life to live and you will love a lot, so enjoy all of this time. Don't treat the dis-interest of a 19 year old girl as any indication of your self worth. I was also 19 and for a female that was a horribly hard time to go through - we're 10 x as insecure as you guys - so the best thing you can do is 1 ) Be comfortable in your confidence 2) Go with the flow - what happens, happens. Don't treat every girl as THE ONE 3)Don't be desperate.It's plain psychology - when someone feels liek they already have someone, hook line and sinker, they don't get to have any of the fun part.

This all changes when you're older, by the way - this is the tough part. Believe me - what I'm giving you here is gold. The more you want someone to notice you and love, the more time you should spend on loving and noticing yourself. SERIOUSLY.. this works.