I really need advice/help.

[BarbieBlonde1]

I am only 15 years old, & I had sex about 12 weeks ago. We used that method where he would pull out. But it didn't work. He cam inside me & we both got really scared. I took a hpt 2 weeks after & it was negative. & then we went to a pregnancy clinic to take another urine test & it was negative. But I am still showing signs of pregnancy, such as feeling sick in the morning & being really tired. Ive had a period since we had sex but it was regular & I have never had an irregular period before. When it started it looked like it was the end of my period but was really the beginning. & it only lasted like 3 days. I saw some really noticable veins in my breast. I have also noticed that I had some white pimping like spots on my nipples & around it. I googled it & it said it was Montgomery tubericals. It said you can still have them without being pregnant but I have never noticed them before. I did tell my granny & my aunt that I thought I may have been pregnant & my Granny took me again about 2 weeks ago to get tested again & it was still negative. Please give me advice about what it could be.