I was preg with DD2 when DD1 was only 5 weeks old.....BUT i wasnt on the mini pill nor was i BF...so different to your case.

AF took 6 weeks to return after DD2 and i was BF her..and wasnt until she was around 4 months old before it came back to 28 day cycles but thats was with the aid of BCP. When she was 5 months old i fell pg with #3 (first month of stopping pill).

I say POAS and see what it has to say!!