Hi, I'm 18. My boyfriend and i had sex for the first time December 8th and regularly since then. Today I've had a really sore stomach, almost like a pulled muscle type pain and lower back pains. I have suffered with my back in the past so thats not concerning me. What is is that I'm due my period around today, even two days ago and it hasn't arrived. Is there a possibility I'm pregnant? We've used a condom every time we've had sex but I'm concerned as my period is regular enough