Partial breastfeeding

Hi mummies need your advice. I got my 1st period on Apr/22 7 months after giving birth as I breastfed my baby and also give formula milk so mixed feeding. However Apr/22 May/22 I got my period , june/22 my period never came and it came back on Jul/22 and Aug/22. Now sep/22 I am 7 days late. Am I pregnant as I have nausea and cramping on and off.