At 20, if your development is the same as a child, are you experiencing late sexual maturity?

Patient's question:

I am already 20 years old this year, but my voice is no different from that of a 10-year-old child. I don't have underarm hair, and my pubic hair started growing at the age of 15, but it is still extremely sparse. My penis is only 2 cm long, and my testicles are also very small, but I can still ejaculate.
Could this be late sexual development, or is it something else like "cryptorchidism"? Or what could be the reason?

Doctor's answer:

You should pay attention to exercising your body now, you can play basketball, swim, etc. Pay attention to nutrition, maintain good physiological hygiene habits, and you will continue to grow taller.