16 years old is too young. You can't even talk to her about sex without using her friend as a go-between. If you are too young/embarrassed to talk about it, you are certainly too young to be doing it.

If you feel this is totally up to you and her, I suggest you sit her parents down and talk about birth control options. Of course, I know you won't do this because (unlike a mature individual) you are afraid of discussing sex.

EDIT: I just noticed that this is the same kid whose girlfriend doesn't even want to kiss him! So yeah, good luck with that...