It is not safe. there is strong risk of bleeding in a 16 years old girl. Moreover, legally even if she gives consent for physical relation , it may not be valid. Better, to avoid it, you need to understand it rather than trying to find safer ways of going ahead. however condom can be used, but remember, if u r taking oral contraceptive pills
, it takes atleast 1-2 months of pill intake to be efficacious. still i would suggest, please stay away from it.