Af and breastfeeding

Ro

So I was pretty regular after I had my son then I got on the shot for 9 months (no period) once I got off I became regular again but all of a sudden I’m not. Currently CD 58, my last period was January 8th. I have been breastfeeding the entire time. Have any of you breastfeeding mammas experience this? Also I have taken a pregnancy test (several actually) looks negative.