I have gallstones. I'm 18, weighs 44kg nd I don't eat much fatty foods. My dad had gallstones and I was on brth cntrl pill. Which caused my gallstones?

Hard to know. Both your family history and bcp use could have contributed to gallstone formation--it's hard to know which was more important. Regardless, you are joining a very large group of people who have gallstones. More important than the stones is whether they are causing any pain--"silent" gallstones require no further treatment.
Several potential. Cholestrin bilirubin hemoglobinopathies! sickle cell probably some more that hers will add!