Why does it seem that my right shoulder looks wider than my left, and my left side of my cheek looks straighter than my right? Is this normal? I'm at stage 4 of puberty, 4.4 by the Tanner Stage Calculator. I haven't seen any growth or change in my voice. My voice still sounds like a normal kid's voice, but it's kind of deep. Do you know when will that change? If I do 60 push-ups and 60 sit-ups every other night, will it get me stronger and bigger?
It is very normal for one side of the body to get slightly ahead of the other side in development, but eventually the other side will catch up. It isn't anything to worry about.
I would suggest that you measure your height once every three months. I often hear from boys who think they haven't had a growth spurt or aren't growing, but they don't realize that growth occurs over a period of time. Childhood growth rates are 1 to 2 inches per year. The growth rate doubles or more during stage 3. During stage 4 it drops back down to childhood levels and keeps dropping until it stops. Because the growth is so slow toward the end, you can see it if you measure often. Any changes gets lost in errors in your measurements. But if you take measurements once a quarter or so, there is enough time passing that any change shows up.
If your voice is deeper, then it is changing.
Exercising a muscle will make that muscle bigger and stronger up until it becomes no effort. To get further improvements, you have to increase either the repetitions or the résistance. But doing just push-ups or sit-ups only exercises a few sets of your muscles. You need to do a bigger variety to get more of your muscles worked. Pick a set to do each day: one for your arms and back, one for your trunk, and one for your legs. But then change them the next day, so you have a different exercise for the arms and back, the trunk, and the legs. That will keep them from getting boring and give you well-rounded set of exercises.