Having 4 kids?!

I currently have 3 boys who are 9, 7 and 1. I’d love for my youngest to have a sibling close in age like his older brothers. My oldest has ADHD and high functioning autism so he needs more attention than the average 9 year old. That’s probably holding me back the most. I have a lot of meetings/apts with teachers, therapists, behavioural interventionists, drs... you name it and it’s hard enough bringing or finding a sitter for 1 little, let alone 2. Ahh but the baby fever is so real and I can’t stop thinking about my 1 year old having a little playmate.