Don't feel that way please. I used to feel the same way. I myself, am a little flat chested. It's not big at all. I'm in the A cups. I also went through a time where i felt like guys didn't like me because of the size of my boobs. My sister's have it, but not me. They always got the attention, and i was always the last one to be liked. But what changed was that one day i was watching this show and they made a joke about the big breasted women. That one day, when they get older, their boobs will be droopy/ saggy. While having small ones, will stay perky. (no offense to the big boobies out there. Not my joke) It made me feel better about mines. Although i still felt a bit sad, but i got used to it and told myself that i don't care what guys think anymore. I'm going to keep being myself, enjoy my life, live day by day and the right guy will come and love me for me. (It's honestly better that way, because at least you know they're there for who you are and not wonder if they're using you because they want to take a peek at the boob). But i can say that i am happy with a man who loves me for me and always calls me beautiful and he doesn't care about the size of my boobs. He loves them just the way they are. Because of him, i don't feel unattractive as i used to. He's made me see, that I AM beautiful regardless of what i see as imperfections on me. We've been together for 4 years and engaged.
So know, that you will find that man regardless of what the size of the 'racks' are. Because if the guy wants happiness, he has to find love, not size in body parts.