18 years old and confused about this dating situation..?

I am eighteen and super confused about myself. I have gone on many dates in the past, but never had a serious relationship. I read all these questions on yahoo where girls are asking "13 and never had a boyfriend.." but that's me and i am way older. Every time I go out with a guy.. he is never good enough or I make some excuse as to why i don't want to date him. I know that's whats wrong with me, but what do you think that is? Commitment issues, I'm just not sure. My best friend has a boyfriend and is happy and I am happy for her, but I never see her anymore, and I'd really like a boyfriend of my own but i just can't get over whatever my odd feelings are. I've had ample opportunities with really sweet guys, but I seem to always dream about dating one of the more hot guys ya no? I must just be a shallow jerk. Help please! I need to be more open I know but now that it's summer I haven't even met any new guys to be open to! And there have been guys that I have liked and would consider going out with multiple times, but the jokes on me.. after meeting with them once or twice, they never call me again or even text. So I'm not sure if its just a game to me or what..i'm a pretty nice person and a people pleaser most of the time..:(