i don't foresee those as being insurmountable

I don't see what the cause of the big outcry over teenage pregnancy is. If age is just a number, then teenage pregnancy is just another time in a female's life in which to get pregnant. For the same reason lower-class adults don't invest their money, lower-class females see no reason to wait to have children -- they never anticipate being in a financially stable situation, so may as well 'spend it when they get it' so to speak.
Besides, if our thesis is that children are capable of handling the responsibility of sex, then that should include the responsibility of birth control. Not to mention, if AOC laws were abolished, there'd be more pressure on parents/schools to discuss sex education and birth control/prophylaxis with their children at an earlier age. I hear much of Europe has ubiquitous condom usage among teens, maybe we should take a hint from what they're doing?
I agree that child prostitution could be a problem, but anti-pimping laws could be strengthened in order to combat the problems you mention. And, we could do in America for child prostitutes what, umm, Nike I think, does for child factory workers in Asia: pay them if they go to school, and don't work.