Pregnant or postpartum?

luna

So I’m almost 5 months pp and so far I’ve had 3 regular periods (period comes when app predicts) and I was supposed to get my period 2 days ago but it has yet to come and no sign of it coming. I’ve taken pregnancy tests and all have come up negative, except for a very very very faint positive this morning that I could only see in person (could barely get a pic of it but I’ll post it in comments). Is it a possibility that I could be pregnant again or is it just pp messing things up?