Pregnant w my 4th but so worried about my 3rd!

So we have 3 kids - 2 girls and a boy. We thought we were done, settled in to life with 3 kids and my son is my baby. He’s 3 1/2 and I just had it in my head that he’s my last. He’s so snuggly and lovey I’m worried he’s going to be jealous or feel left out. Both my daughters were soo excited when they found out they’d be big sisters and fell in to the rolls like old pros. I of course worried about them still but not as much as I am with my son bc of how excited they were / are. He’s a mommas boy and i guess I’m having a hard time too (I’m only 7 weeks so it’s still really sinking in). I am happy and excited to have another baby even tho it was a huge shock and I know they’ll be so loved and complete our family I guess I’m just having some anxiety. Has anyone else gone through this?