For the past few days, my stomach's been hurting

So last week I lost my virginity to my boyfriend, we're both sixteen, and it was our first times. It was on July 24th, and it's now August 1st. My period had ended about two days before. We had protected sex, he used a condom, and he pulled out, then he came in the condom. He hadn't touched his p***s before that, at all. I only bled a tiny spot after but it hurt down there, only for the rest of that day. 

For the past few days, my stomach's been hurting. Yesterday and today my stomach and lower abdomen look bigger and get big right after I eat. 

My breasts aren't sore, I'm not tired, and I haven't eaten a lot. My period is supposed to come around August 19/20 or around those last days of August. 

I'm really worried that I'm pregnant, could I be? I really hope I'm not. Please help me. I really need answers.