How soon did you start TTC after having a baby?

My second child is 11 weeks old and I've just had my first postpartum period. and I'm already thinking about getting pregnant again. my doctor recommended waiting at least six months to get pregnant again, but two weeks ago we had a scare where we thought I was pregnant with #3 already and I had already kind of gotten excited about it before I found out I wasn't really pregnant, and I'm honestly a little sad about it. I'm trying so hard to wait the 6 months after baby until September, but I keep thinking it wouldn't be the worst thing in the world to have an accidental pregnancy before then...