Not crazy at all!
I was already TTC by the tiem my first was 12wks old and pregnant by the time he was 6mths old. This time round we were TTC but werent preventing as we have fertility issues and I got a BFP when #2 was nearly 5mths old. There are 15.5mths between #1 and #2 and there should be on or less than 15mths between #2 and #3.

Its mega hard work I can tell you that much, but if its the right thing for you guys then go for it! Talk it over with Dh as well.

Good luck!