What could it be?!

Okay ladies i have a question. So im on the pill however i been messing up a lot and missing some but taking them the next day. The first time I had sex with my SO with no condom, well at less than 48 hoursi took the plan B. We had sex again 2 weeks after again no condom but that time i didn't take plan b. Ive had my period but i only had it 2 days instead of 5? I just ate and felt very nauseous and felt like puking? I've also been having random cramps like a period. Im not sire if i should or shouldn't take a test do you guys think i can be pregnant? Or should i just go to the dr?