If it's not too heavy sounds like it might be your period. I was quite surprised when I got my period 3 months pp. Loads of people don't realize you can get your regular periods back while breastfeeding. However, of you think it's too heavy for a period I would insist on getting checked. Have you already had your 6 weeks pp check..maybe you can use that?
Yes it could be your period. Mine came back very early despite EBF :)
This happened to me and was my period, that was despite bf.
Period possibly?