I'm a 15 years old guy who is 5'7 and there are 14 years old guys who are taller then me. Is that normal? I'm only 2 inches when I'm soft and 4.5 inches when I'm hard. Is that good for my age? I also have some hair under my armpits. On my left armpit there is a little bit of hair and on the right I have a lot of hair. Is that normal? I have a lot of pubic hair so I guess that is ok. Which stage of puberty am I in?
Lupe (age 15)
Everyone grows at different times and at different rates. Even though a 14-year old boy may be younger than you, he might easily be further along in the stages of development. Also, everyone will end up being different heights when they are an adult, so some boys who will be very tall may be taller than you even though you are more mature. I'm six foot, but I know a boy who was taller than I at the age of 12. Everything depends on the individual.
When growing everything doesn't always happen on the left side of the body at the same pace as the right side of the body. Some unevenness is normal. Even after you are fully mature there can be differences in the amount of hair between the left and right half of your body. So what you are describing is normal.
As far as what stage of development you are at, see the Tanner Stage Calculator for Boys. But regarding your penis size, it would be fairly typical for a teenage boy.