Not a good idea. Too young. She needs to have her chance to grow up and really decide what she wants . Living with her boyfriend may restrict her from becoming who she's meant to be. Perhaps becoming too dependent on you. If she loves you and it's meant to be then allowing her to grow up more won't hurt . It may help your future relationship. You had those few years. Let her have hers'
Depending on what state you live in to have sex with her can be legal or not. But usually 17 now has become the legal age for sex. I don't think you guys should move in2gther. You and her both have to grow up. I lived with my boyfriend wen I was 16 and it was a terrible mistake. Finances and dealing with the real world at such a young age put a strain on our relationship and we ended breaking up.
Well dear you are too young to take the responsibility of a 16 year old gal.See if you guys really love each other then I would suggest to you to give sum more years to mold this relation and once you guys are matured enough to face the reality of life then just go ahead .
At 16 the issue is more that it is illegal to have sexual relations with her. I would definitely hold off on moving her in.