Ok... so I will probably sound harsh, but it is with the best intentions ok? I'm going to take the role of harsh-critic-blunt-friend. And it is ONLY based upon your posts in this thread - there is a lot about you that I am clearly missing!

1. Your lack of confidence in yourself will in fact show up quite quickly in conversations.
2. You can in fact change your eating habits. Even if you don't lose weight, you'll be healthier. (Plus, if you went from never working out to biking lots, you were probably also gaining some muscle).
3. Prositutes will give you a warped perception of women - it's not helping you at all. And a lot of women will definitely not wish to be in a relationship with someone who's gone to lots and lots of them. (Then again, not everyone! There are also lots of women who won't care because it's your past.)
4. What sort of job do you have? A lot of people care to see that potential partners have a stable career (then again - not everyone! and "stable" doesn't mean "earning lots of money")
5. A smile and brief random conversation really doesn't mean "hey I want to date you". It means that you smiled and were friendly. Not everyone will interpret that as sexual desire. I wouldn't! I'm quite clueless.
6. Therapy would be quite beneficial because you don't seem to have a very positive view about anything at all (then again, you're having a rant!) and you've mentioned problems since childhood. Therapy could help you manage that and recover a bit.
7. It sounds like you just meet women in bars? Try joining up with social groups in your area to meet people who would have similar interests. Or do some volunteer work. If nothing else, it will help you develop more social skills.

There is a lot that you can do to help improve the quality of your life. Quality of life means what do you have going on in your life that is meaningful to you? Do you have a job that you enjoy? Are you happy? Are you taking care of yourself physically and emotionally? A lot of the time, when you are happy with your life you're more receptive to finding a healthy relationship - and it shows when you meet people.

If I were in your situation... I'd focus on your health and your addictions (protitutes and junk food) and get some help dealing with your past traumas and low confidence in your social skills. They are all barriers.