If you're not religious, why are you in such a hurry to get married?
Teenaged marriages have poor statistcs when it comes to them being happy long term ones.
No doubt you will be convinced that you are one of the exceptions. Just like millions of other teenaged couples that have hated each other's guts by the time they were 21 to 25.
Ideally you want to be a free agent when you go off to uni. Ideally, aim to have a few boyfriends whilst you are at uni.
Your boyfriend will lack the maturity that's required in order for him to be a good husband (because he's 17!). Don't marry him!
Also aim to live with someone for a year before deciding whether to marry them or not. You want to get past the honeymoon phase to have a better idea if you will be happy together or not in the long term.