hey,
i totally understand what you're saying. when you break up with someone, it sucks and there are a LOT of times when you feel just really lonely and insecure and messed up..believe me I've struggled with this a lot. but that does not mean you aren't good enough. it just means you haven't found the right person...and in all honestly, you shouldn't try so hard to look for him. have you considered that maybe the reason why you're ending up with this ass-hats may be because you're trying to hard to find anything that could be love? it just doesn't happen that way. it's got to be right for both people...right in a really cool, very real way.
i know it sounds like a copout...but take it from someone who's been there. wait it out. get to be comfortable just being yourself, be comfortable living and relating to yourself. people in general, not just guys, like a person who's okay with who they are, and don't need to be with someone to be happy. once you're happy with you...then you're going to have all of you to offer to that one lucky guy who's going to cherish it.
whew...so yea, that's REALLY cheesy...but I swear to God it's true.
hope this helped ;)