What’s big to you is totally different to every other individual, one may think a c cup is big example where as you may think a. D cup is big that goes the same to every surgeons,
There are some guys who get nervous as they think you will leave them as your bettering yourself but afterwards they absolutely love it and besides they care so most likely your boyfriend doesn’t want you to look out proportion.
With all that said it’s your body BA is what you want and not for. Anyone else and the size that you’ve been offered isn’t as big as your boyfriend is thinking. Goodluck! X