After DD1 it returned pretty much the next month (hence me falling pregnant with DD2) and their 11 month age gap.

After DD2 it returned 6 weeks post birth

After DS is was around 7 weeks post birth

The main difference was DD2 and DS were BF or i was expressing....DD1 pretty much was on formula from day 2.

So to answer you question, yes AF can return so soon!