Missed AF

According to this app, I was expected for AF on November 24 & I missed it so it changed my period for November 26 (TODAY) & I didn’t get it again. I did have intercourse w my SO 2 weeks ago on my most fertile day & he came in me. My periods are very irregular also.

I’ve been having cramps in my lower tummy for almost 2-3 days now. Oh & we do have a 14 month year old daughter.. could I possibly be pregnant?