hmm, do you not like yours because YOU don't like them, or because your bf has given the impression he hasn't?
I'd say you could try and find influencers with a style you like with a similar chest size or something to help you feel better about it?
I'm 18 and a 32AA but it fits my body type - I've learnt to dress for my body and I genuinely don't mind my chest size anymore. I will say when I was with my ex (my first boyfriend), I did start to feel insecure even though he constantly said how much he liked them because I was so sure all men like big boobs. I'm not sure why that is, it could be something to do with porn or what the beauty standard is at the moment, but I think if you focus on your personal style you'll get happier about it. Also B-C is not small, it's completely normal!!