My children. Advice!?

Ugh, maybe I'm being to sensitive? I don't know, I'm just sick of the comments that my SO should get snipped (as his mom said countless times) and his friends are like you're having another kid!? My SO already has two kids, and I am currently pregnant for the first time. I'm just getting sick of the comments about him having more kids, this is my first child! I love my step children a lot!.. but they aren't mine! My SO wanted to post on FB "having a kid again and it's a baby boy." I got slightly upset and made sure he understood it isn't "again" as this is our first child together.. that we together made a baby. I want three children, and yet everyone makes a big deal out of it because he ALREADY has two kids. I don't know, it just grinds my gears. I want my own babies, I don't care if he had two kids already but they aren't mine. I didn't give birth to them, I want my own children. I don't like comments like that, as I want my my own children I don't want people to say he should get snipped because he already has "to many". This is our first child together and people already say such things and yet I want more.. I can't imagine the comments than 😕. Any advice? I'd really appreciate it!