If it takes you 6 to 8 hours a night to do your homework, you are doing something wrong, or must also be looking at facebook, instagram or responding to numerous texts. With a course load of 6 academic subjects, each requiring a half hour of homework, you should be DONE in three hours or less. Anything more is overkill or demonstrates you are not grasping the material in the classroom and could not also do the same if admitted to Yale.
Just having a lot of extra curricular activities does not make you a better candidate. Without knowing exactly how involved you are in these activities, how long you have been involved and whether you have any leadership positions, it is impossible to tell. I would suggest as you move into your senior year that you concentrate on one or two of these activities where you can show sustained involvement in a leadership position. It is one of the first questions I ask candidates I interview - tell me about one of your extra curricular activities, why is it important to you, how many hours do you commit to it each week/month and what positions have you held. It is definitely quality over quantity and I will take someone with one or two ECs that reflects their passion over a candidate with a laundry list of 10-15.
Good luck.