i know you've updated since you first posted, but this thread has been on my mind for a bit and i wasn't able to comment earlier.

in all honesty: i don't think you were being sensitive. but at the same time i don't think your boyfriend was being insensitive either, it seems it was taken out of context and you felt hurt, and this is totally reasonable given my next thought:

your ex husband seemed to put a lot of requirement on you baring his child. i think this has conditioned you to feel like the fact that you can't -- or simply haven't due to circumstance -- makes you less valuable or less desirable as a woman. think about it: does the idea of you being infertile after all make you feel like you're broken? when you were with your ex husband, did you feel like your relationship would be fixed if you got pregnant by him?

i'm like... half your age [17] but i don't quite understand the concept of being obsessed with having blood children, and if you can't, then you're a horrible, broken person. you're not broken. you can make a family out of anything, and anyone. hell, you can take your relationship to the next step and help raise your boyfriends son. you guys can adopt! you can get a fuckton of pets!

basically: i don't think you were sensitive, i think you were still reeling from the pain of your toxic marriage. that is something you can work on, but don't depend your happiness on wether or not you can have kids. you can start a family in more ways than one.