A little nervous..

So I am on birth control and my boyfriend and I always wear a condom as well. The last time we had sex was probably 2-3 weeks ago. I just went to Europe and I was extremely nauseous on the plane, I threw up. I was nauseous on the way home, all the way until I fell asleep last night. I was hoping I'd be good today except I'm starting to feel nauseous again, I just ate a big meal and I was thinking it could be because I haven't eaten in a while because of the nausea. Do you guys think I could be pregnant? I take my pills mostly on time and haven't missed one this month.