Scared to conceive

Have any other moms had that nagging feeling that it's time to have a second (or third, or seventh) baby but been terrified of actually doing it. Logistically I think it's best for our family to have another now. I've weighed the pros and cons and feel that the pros outweigh the cons but I'm so scared to have 2 under 2. I know this isn't everybody's choice but for our family and our timeline with careers, family dynamic, path, etc I do think it's the best. But I'm so hesitant to actually try for #2 because I'd have an 18 month old when #2 is born if I conceived tomorrow. I don't want a 2 year or more age gap because I don't want to get out of the baby phase and get sent right back in and I don't want my first to be jealous or feel replaced which tends to happen with a 2-3 year age gap.

Has anybody ever felt this and conceived anyway? How did it go?

Is this a normal fear to have?

Anybody with an 18 month gap between their kids care to give me some words of hope?