Whens best to have another child?

Just wanting too know when the right time is to have a second child. I gave birth in February and my little girl is 20 weeks and me and my partner want another one. I said we could start trying next year after my 21st which is January 2nd (my birthday).

I know people that had a baby that's now 1 and currently pregnant or had their little one.

looked online it says wait 1 1/2 years (18 months) so it gives your body time to recover and prepare from the next pregnancy.

My labour was amazing but after I had my little girl my placenta got stuck and complications started. Lost so much blood rushed to theatre got cut down below. Forceps delivery. blood transfusions. Massive hemarage and blood clots.

any advice would be great