Curious🤔

Hey everyone I'm 26yr old and I have been with my boyfriend 9years and have 3kids with him. In between my kids I have had 2 miscarriages. My youngest is 2yrs old and since we have had sex with out any type of birth control. Not that I want to have anymore kids at this moment but if it happens it happens...  but he cums inside of me all the time and we have sex like every other day but I have not gotten pregnant. Could there be something wrong with me ... Not to be funny but I'm curious