Still looking to move to america, is this possible?

actually, you wouldn't be eligible for an L-2 visa under legal guardianship no matter what your age is. you would have to be formally adopted. so, maybe you can't go to a public school there on an F-1, but you could go to a private school on that visa, and they are much more likely to be willing to issue you an I-20 and register you in SEVIS.