I can see that your dad need's to have a life too and probably doesn't want to have to explain everything to you but still I do believe that you need to be enjoying your teenage years and not having to be 'mother' to your borther.
I am not trying to sound horrid to your dad or anything like that - as you said he said you guys work as team.
Your teenage years are precious and for me, were what defined me as a person. I want you to be able to have the same thing.