Serious question...

This is probably a dumb question but can you be pregnant and still have your period? I know there is a show where girls are pregnant but don't know it until they give birth but I don't know how accurate that is. I'm worried because I'm tired all the time, smells that used to not bother me make me want to vomit, the other day I went to drin a glass of milk and was instantly repulsed because it smelled sour but everyone else said it was fine, I'm craving food I normally can't stand, good I eat all the time doesn't taste right and I'm always hungry but when I eat I only take a few bites and am done or I eat like I haven't eaten in a few days. And I swear my tummy is getting bigger. I have an appointment with the ob on Monday and I'm going to ask her but it's driving me crazy... Please help!!