It is different with everyone. Some will get AF back like clockwork as soon as lochia has stopped while still BFing, others will go right through their BFing journey (some 2 years & more) without AF!
Mine returned when DS was 9 months old, but didn't go back to a normal cycle. Mine was 6 - 7 weeks apart for 3 cycles, then I went & got my depo shot, which stopped it, so I have no idea where it would be now.
I think there's every chance yours may still be a bit out of wack. I think my body was just having kind of break through AF & I might not have even been ovulating... I really don't know TBH.
Definetely do another test, or go check with your gp if you are unsure though