I had sex last week for the first time. We used protection but I've been having some weird pain in my lower adomen. I lost track of when my last period was.Can I be prgnant?

Used protection ? You where holding a 9mm gun in case someone robbed you ?

What protection, you are on birth control pills and have been for a few months ? You used the morning after pill ? Or did you just use condoms. Condoms are better than "pulling out" but still have a high failure rate, often because they are used wrong. But condoms have from a 3 to 10 percent failure rate.

So can you be pregnant, yes of course, you are going to have to wait to see if you have your next period. So did you have one last week ? If no, then we know you should have one in a couple weeks most likely ? So you wait three weeks and if no period, try a pregnancy test