painful sex and low sex drive

Hi guys! i dont know what to do. so i have been in a relationship with my boyfriend for 5 years now, and in the beginning of our relationship we used to have a lot of sex. like we could have sex anywhere and we would both be horny. sex also didnt hurt then. i have also been taking birth control since the first year after we started dating, so when we started dating and having sex i was not on birth control. for the past year or two (which sounds rlly bad) i have not really been that horny. i will get horny here and there but its always my boyfriend that is initiating sex, and when he initiates it, i dont want to sometimes. when we have sex, certain positions are very painful. my gynecologist told me that i have a tilted uterus, so this makes sex more painful for certain positions. whenever we have sex im just scared that its going to hurt and i dont enjoy it as much as i should. my friends always talk about sex and how they want to do it but i cant relate to them because i can go without sex for awhile. i dont know whats wrong with me and i want this to be different if someone can help me out. Like i wish i was more horny but i dont know how to fix it.