To the OP--
The whole reason we have age of consent laws is that there is a power imbalance between young adults and teenagers. Because of your actual physical age, you have the ability to inappropriately influence this girl's sexual development. The ability to manipulate her.
Even if you are not sexual with her, you are in a relationship with her as a metamour. That's real. That's a grown up thing. And that's a place where you have this ability to do her harm, simply because of the power imbalance.
The imbalance exists with your boyfriend, too. It's not criminal, but you skirted the law so closely, there's still the possibility that the authority you wage with your age could be used in a bad way.
The fact that you say you *need* him? Big red flag.
I'm not saying that you are harming these people. I'm saying you have the ability to harm them. It's up to you, what to do with that.