Yes, I have a letter just like that in Private and Personal. Yes, it's normal. Your smaller breast may catch up if you are still developing. But many women are slightly asymetrical , and there are special bras you can look into too. Chances are things will even themselves out.
People have different tastes in guys and that's normal.
But if she really is going down the wrong road, don't give up on her. If he, for instance, hits her, I think it would not be tattling to try and talk to her friends or others to help her see that she deserves a boyfriend who respects and loves her. And I think honest relationships are the very best. But right now you are in hot water, and if you want to get out and dry off and try to make your ongoing relationship work, then maybe you shouldn't confess all right away. Well, I really want birth control pills but dont want to ask anyone, but would ask my doctor only .