Thank you for sharing your question with the EmpowHER community.
If you want to prevent pregnancy, the best thing for you to do is to always have condoms and use them every time. Even if the young woman you are engaging with says she's on birth control pills, you completely relying on whether or not she is taking them correctly is the issue.
Outside of using a condom, you could use the withdrawel method, but that is very risky. Besides that, the only other method that you control entirely is abstinence. Condoms also protect you from STDs as an added bonus to preventing pregnancy.
Also, as a last resort, if you have an emergency situation and you have had unprotected sex, there are emergency contraception pills available that the young lady can take to prevent pregnancy. However, this is not something used regularly or in the place of true birth control methods.
So suggest you stock up on condoms and always be prepared.