i just tuned 15 about 3 months ago and my gentals still haven't gown I have plenty of pubic hair and facial hair and even some armpit hair... But my gentals still haven't grown is that normal
I'm sure they've grown.
Average for an ADULT male is 5.1". For a 15 year old, 4-5 but it can vary depending upon when you started puberty.
You are developing normally from your post.