Well, your legal guardians have responsibility for your well being, as you are considered a child by law. They would be well within their limits to pursue legal actions against your boyfriend were you to live with him.
Another consideration is statutory rape. If you are living with your boyfriend and sharing your life with him, the assumption would be that you are probably sleeping together - again, he could get in very serious trouble for this.
One other thing to consider - living together, at any age, is a huge step. It will bring added pressures to you and your relationship. Because of your age, your focus needs to still be on education...while your boyfriend will be responsible for supporting you both. Is this fair on either of you? Does this stop him from reaching his goals?
What about you? Can you withstand the daily pressures of living with someone, no matter how much you care for them? In addition to bills and practical considerations, it's a lot more work than fun. You will be exposed to all of their flaws, and they will be exposed to yours. Is your relationship stable enough to handle this?
What affect could this legally have on your boyfriend? On your relationship? What long term effects could this have on your relationship with your parents, your education, the stability of your future?
I realize I've given you more questions than answers, but this is a huge committment - and in your case, an illegal one. Moving in together can require tough compromises and deep committment in an average situation, and the added complication of your ages will necessitate even more thought than usual.
Best of luck.