Which contraceptive does not gain weight?

I'm 16 years old. I already have an active sex life. I'm allergic to condoms, I want to take more fattening contraceptives. I wonder if there is one that does not have this side effect?
Expert answer:

In theory this is not true, contraceptive does not gain weight, some women may have some fluid retention and others may have increased appetite, however the contraceptive pill does not have any calories it is "diet" then not fattening.