Should I be worried?

So I have been single for eight months. Last month I decided why bother with bc pills if I'm not having sex. Low and behold I had sex on Nov. 15th I have known him for yrs and we dated but had a falling out. We both still have feelings. He has always wanted to get back together. Anyway real issue here. According to Glow I'm a week late. It was supposed to start on the 24th. I took a pregnacy test on Friday and it was a strong negative. However; before bc my period was irratic. Should I test again? Or could it be a side effect of coming off bc? Thanks!