4 months PP- pregnancy?

Erica

I had my 2nd baby a few months ago and I’m breastfeeding, haven’t had a period yet. With my first I didn’t get my first period 4 months after STOPPING breastfeeding. I’ve been having a couple days of cramping and lower back pain and today nothing. Haven’t had a period. Could this be a sign of pregnancy? Or is it just my body being weird post partum?