I assume that you are very young, so I would not make life-altering choices now (vasectomy). You have so many years ahead of you that you might change your mind later.

You can protect yourself against STD's via a combination of vaccinations (some STD's are vaccine-preventable) and religious use of condoms. Taken together, these measures afford a good degree of protection, but not 100%, of course.

Condoms that are used correctly protect against pregnancy very well, but, again, not 100%. So to make sure the girl does not get pregnant, she should be on a reliable form of birth control (something that is at least 99% effective) and you should use condoms. For that kind of an arrangement, the girl should be trustworthy. This girl who told you she wanted to have your babies while winking at you - is she trustworthy in that respect? Think hard .