Could I be pregnant??

Alex
I am not a virgin and I'm 15, which I regret. But anyways, my boyfriend and I were fooling around but we didn't have sex. This was the day after my last month's period, He pulled out his penis and put it near my vaginal opening, I grabbed it and told him I don't want to have sex and we didn't. After that it freaked me out that his possible precum got on me, my period was supposed to start on the 13th of April but is now 10 days late today. 13 days after we hung out I got into a car accident and when I was in the hospital they asked me if I was pregnant, I told them no and then they took a urine sample and took it away. After awhile they came back and took me in for x rays (that's why they tested my urine right? To see if I was pregnant?) But now I told my dad's girlfriend about all of this so she told me that it's impossible, but I insisted on her buying me a pregnancy test (Walgreens brand) to see if I was pregnant, it came out negative. I have been stressing about this since the night him and I hung out together that I could become pregnant. I feel like it's the stress making it late, maybe the car accident messed up my hormones. My dad's girlfriend making me an appointment with the OBGYN but I want to know if its possible I could be pregnant from someone with experience, also if they test you if you are pregnant no matter what before x rays. Thank you very much.