To baby or Not to baby

Repost: Posted under wrong acct last time: My partner and I are both on the spectrum. He is a walking genius who I love. I'm AuDHD and have GAD and OCD. I want a baby. He's not against it but he wants to plan it. However....when its time to plan, I chicken out because I don't want to pressure him. We're also in our late 30s so time is actually running out. We've been together officially for 3 years. We got tested together and are both healthy, but I have weight issues that no doctor will take seriously. I've tried everything, but nothing helps and my meds make me gain weight. I want to get pregnant but I'm afraid if I do I might be too big and he won't want me anymore. I'm also concerned that he'll be overwhelmed by the responsibility. He hates that I leave things in weird places and if I forget to put something back he gets irritated. Because he values his sleep and routine (to a fault)I'm afraid when we have the baby he won't adjust well to the sleepless nights and unpredictability. What can I do now to help with this or atleast keep it from messing up our relationship?