I'm scared! What am I experiencing?

I'm 18 years-old and about to graduate. I'm still a virgin but I have a boyfriend. A few weeks ago when we were making out we touched each other and he did have a little pre ***. This soon after that I was always hungry and ate a lot. And I got a lot of gas. I didnt gain any weight. But this past week my have been kinda sore. Mostly on the outside by my armpit and underneath the . They usually dont hurt unless they are touched but every once in a while pain will just shoot through. Also , my themselves are not sore, they seem sensitive (usually are) but they dont "hurt". I feel like they may have swelled, but I cant really tell. I could just be making it up in my head since I'm paranoid. Also my appetite all of a sudden decreased drastically. I believe it has to do with my irregular and infrequent bowl movements. So I suppose Im constipated. I also pee alot. I dont necessarily have the urge to pee all the time, but when I do pee, theres alot. I had had some crampy pain in my lower abdomen, but thats subsided. Mostly just my and constipation bothering me. When I wake up I'm not tired but its hard to keep my eyes open, not sure if that goes with these symptoms, but I found it odd. My period is due any day so I havent taken a pregnancy test. I just kind of want to get people's take on what could be going on. Is it just an impending period? Do I have a medical issue? Or do I have a miracle child growing inside me? I'm kind of really worried. Please help! Thanks