Hello mommies, this may be kinda long so bear with me!

A month ago I switched from the merina to the pill. I started the pill the same day I got the merina taken out! I told my SO he needed to be careful till my body adjusted too the pill, well here it is a month later and I as supposed to start my period Sunday, I have yet to start, no signs of starting, my question is could I be pregnant, I don't have any symptoms of that either! Last week I felt nauseous and took a test and it was negative!!! Advice please and thank you!