I missed my period

Rayne
So I missed my period, it was supposed to start on the first and here it is the 8th and no period. My boyfriend and I have sex regularly and I've never missed before and I've had cramping, sore nipples, back aches, headaches and nausea. I even went to my doctor last week and they said that I'm not pregnant and I still have these symptoms 😱 when I started having these symptoms (about two weeks ago) I stopped taking my birth control pills. So I'm not sure if that's a factor? Helpppp please!!!!!