I hope you doing well. I want to know if my muscles will grow further and whether my testosterone will increase after this. I’m in Tanner Stage 4.4. I also wanted to know when will I have a beard. This is what it looks like now.
When males get to stage 4, they are able to build muscles. This ability remains with them through adulthood. However, the building of muscles requires exercise. Muscles don’t develop on their own. See Is there anything I can do to increase muscle mass other than weightlifting?
Your testosterone levels are highest during stage 4 and then settle down a small amount to your adult level. See Should a teenager have adult levels of testosterone? Your adult level should stay steady and very slowly drift down as you approach your elderly years.
As you are noticing, a male’s hair doesn’t come in all at the same time. There is a reason for this. Hair cells cycle. They have a period of growth followed by a period of rest. During the period of rest, hairs will break off. The hair cells on your scalp have very long cycles. The hairs on your arms and legs have short cycles. That is why your leg and arm hairs don’t get overly long. If the hair cells cycled all at the same time, you would shed like a dog or a cat. But by having the cells’ cycles staggered, the appearance remains the same. Therefore, it takes years for all the hair cells to develop. As time progresses, your beard will get thicker.
In the meantime, you can shave the scattered hairs so that you look well-groomed and then when you think enough hair is there to form a decent beard (in six months or a year), you can stop shaving and see what you get.