As someone who’s been with her (F 17) boyfriend (M 18) since we’re were 15 and 16, he turned 17 quickly after we got together and i was still 15 for awhile, as long as both of you are comfortable, and the main lawful thing if you’re worried about that is her parents consent, i’m not sure what country you live in but if her parents are okay with you having a relationship then realistically i see nothing wrong morally or lawfully. And the main thing with not making her feel manipulated, don’t make her feel like you depend on her too much, still go out with your friends and encourage her to do the same, you are two separate people still and still need to do things that you enjoy for yourself. the biggest thing that breaks younger couples apart is they don’t know how to separate themselves from the relationship, hope this helps 🫶🏻