Is something wrong with me?

You could be stressed out, and you probably need more sleep. most teens should get at least eight hours although focusing on a specific number doesnt make you fall asleep sooner. Peeing every two to three hours seems pretty normal, and the back pain could be from stress, lack of sleep, your bed, or a number of things like you mentioned posture. Idk about the stomach though that sounds weird about the pushed in part, but the fat perception is probably just from comparing yourself to unrealistic women in tv and other media sources. tummy aches can be caused from stress also