Am I pregnant? Please Help!!

Hi my name is Candi and I’m 16 years old. I had sex using the withdrawal method on May 24th and 26th. I had just finished my period on the 23rd. The first time we did on the 24th I dont think he pulled out in enough time, and I think SOMETHING did go in me. A week later I started feeling dizzy and faint, and nauseated when I smelled certain foods. The following week, I was very tired, I began to urinate very often,(sometimes in the middle of the night) and my appetite increased heavily, I began to get hungry in the middle of the night. I also took a pregancy test on this week, but it was negative.
The week after that, I was extremely tired and sluggish, my stomach me began to get tight and became larger. This week I took another preganancy test and it was again negative.
The next week, (June 20-26) which was the week my period was due, my stomach was EXTREMELY tight and even sore near my lower abdomen, and very solid there also. On June 25th, my period came(or atleast I think it was my period) and it was regular for 1 day, then it became very light almost nonexistent. This light bleeding has lasted for 5 days, and this is the 5th day.
My breasts are a little sore, which has NEVER happened to me. And my veins in them are VERY visible. My nipples look darker, and when I rub against them it makes me cringe. Am I pregnant or is this just my imagination?