I have a really small flaccid penis but a large erect one. I am 13 years old and my penis measures 1.5” flacid and 4.3” erect. Is this much size difference normal? And will my penis grow? I have already started puberty.
It's perfectly normal.
You are what is called a "grow"-er. Some guys are "show"-ers (big all the time).
Average for a 13-14 year old is 3-4" erect. There are no real averages for a 12 year old.
Your penis can continue to grow into your early 20's. Average for an adult male is 5.1" erect.
Hope it helps.