How long would it take to get pregnant after using nustrate injection for 3 years?

Assuming you mean noristerat, it will prevent conception for at least 8 weeks after the last dose, and it could be as long as 12 weeks. How long you took it before stopping makes no difference. In fertile women with no contraception, on average it takes up to a year of regular mid cycle unprotected vaginal sex to conceive, so don't worry if it's a few months.