My bf 15M doesn’t like my chest 15F

Hi, I am kinda flat chested girl, I am A cup. When I was younger it was never a problem but now I hate them so much. I started dating him in October. Then in December I decided to show him my chests, when he saw them he look disgusted, I don’t know how to explain his face expression, but that really hurt me. He never touched them or kissed them or told me that they are pretty. When I confronted him that he hates my chest. He said he didn’t know how to react. Now he started touching them and kissing but I feel that it is forced and he doesn’t like them. Also his friends in November said that, I am flat and that my bf has bigger chest than me.

What should I do? Does he like my chest or no?