Do you think im pregnant? ? ?

Is it normal that after losing my virginity I'm scared about being pregnant. I had sex 4 1/2 months ago for the first time...we used a condom. I'm now scared about being pregnant. I had my period every month after losing it but now it looks like my stomach is getting bigger. I was thinking that I could just be getting fat because its the summer and basically all I have been doing is eating, sleeping, and watching t.v. I really don't know if I'm pregnant or just paranoid. The only symptom I'm really having is that my stomach keeps growling and getting kind of hard, I don't even think that is a symptom? What do you think? Please help