Pregnant again and afraid (but want) to tell my parents

So for some background, I'm 27 years old, living with my fiance, and 7 months ago I had my son at 32+1 after an emergency cesarean section due to severe preeclampsia. He was also only 2 lbs and 13 oz, an nuchal cord ×4 (meaning his cord was wrapped around his neck four times) in between then and now it's been hectic with my family. Fights broke out between my friend and my grandma, someone called social services 8 days after I brought my son home from the nicu, and I have reason to believe my parents were responsible for that call. After the water calmed, my family spoke to me and said absolutely no more children. My grandma said I'm too poor, and my parents insist I'm never going to be healthy enough for more than a one and done.

As mentioned, I'm now pregnant again, and only seven months postpartum. I'm aware of all the risks, and intend to do everything in my power to make this successful, I feel good about it and good about myself. I feel like I'm glowing. But I feel like my parents can see right through me, and it's kind of eating me alive. My fiances family knows, and are all excited for a new one, but can i really just hide under a rock from my parents and grandma until I deliver? As much as I don't trust them, my mom is my mom and everything relative I can talk to her about day and night, with the exception that she tells my dad who tells his mom. I dunno. This whole ordeal makes me feel uneasy.