Hi Doc, My Penis Size And Girth Are 4 In(erected)

Hi doc, my penis size and girth are 4 in(erected) [1.5-2in (non-erected)] and 1.5-2 in (all sizes are in approx.) respectively. I had undergone an operation when I was 14 or 15 on my penis because., one night my foreskin got stucked back side of the penis and was unable to retract so anyhow they(doctors) did some operation and they were successful.
Now I'm 22, my foreskin is bit tight to pull back and forth, so kindly him me some suggestions what to do or not. I want to increase my length and girth size.
Thank you.