To want another baby already?

[UterusesBeforeDuderuses]

I've got a 9mo DS and have been back at work from maternity leave for a couple weeks. Up until a couple months ago I wasn't even sure I wanted another baby at all, let alone any time soon (horrible pregnancy and birth, followed by PND) but suddenly I find myself constantly thinking about getting pregnant and having another.
DH and I always said we'd have 2, and I'm wondering if it's a good idea to have them close together, partly so they're quite close in age which might be nice for them, and partly so that I can kind of get the pregnancy part of my life out of the way and have kids while I'm still relatively young (I say 'young', I'm 30, but I don't want to be having a baby in my late 30s)
Can anyone give me advice on whether having kids close together in age has been positive/negative? Is having 2 under 2 a truly terrible idea?

I personally wouldn't, for financial implications mostly.

If it were me, I'd aim to be going on mat leave nine to twelve months before DC1's free hours kick in. Then when I went on mat leave and had a drop in pay, I could pull DC1 out of childcare and save the money there. When mat leave is up, DC1 has their free hours and DC2 has childcare costs. Versus a couple years of double childcare fees.

Obviously things don't go exactly to plan with TTC though.