Stop panicking, that sounds like a reasonable length for a 13 year old and also it will probably grow more.
About average
Roughly 3 and a half inches errect
No.
You're ok.
What to do when penis still in 4 inches even he is 21
Nope it will shink!
no it's normal.
This is about, or just over the average size erect penis for your age.
There is no 'normal' size. It varies depending on the person. 6.5 inches is in the normal range for most males.
12 inches!!!!!!!!!!!!!!! 7-12 inches!!!
A normal 24 year old would have a penis of between 5 and 7 inches long.
I'm 15 and i have a 8 and 1/2 inch penis and the average penis for a 15 year old boy is 6.2 inches when erect and 4.1 inches around