Newbie to sex

Hey ladies, I am seventeen and recently lost my virginity. I have not had any desire to have sex again, (not that I had very much before.) And it wasn't that the sex was bad, it was simply uncomfortable. I have a Mirena IUD and I do not think that was the reason for my discomfort, but it felt almost like he was pressing up against it and I also couldn't even sit up while being on top because the pressure was so intense on the front side of my vagina.