I am going to get my next HPV shot from the doctor in about three more week from my doctor. My father tell me if I carry my book bag that it could damage my arm or my body. My book bag is about 13 lbs book and stuff. I am going probably have before I go to school. Then I will be heading to school on the city bus. Too me do I need to be nervous.

No reason to be nervous. Carrying your bag won't injure your arm. You might have a sore arm, but you aren't going to damage it.