Even my endo said that the hand x-ray is just an estimation, that a knee x-ray would be needed for a definite answer. However, you are correct, I probably will not get any taller.
the x-ray method is accurate in my experience. i had an injury at 15, and the doc noted that my plates had already closed. he was right on.. didn't grow a centimeter after that.
Yes, everyone is different. I was on the other side of the spectrum. I was a full 6 foot tall in 8th grade and didnt grow a inch more after that. Im still 6 foot tall at 38 yrs old. Heck, once we reach a certain age we begin to shrink in height. Things dont get any better! The intervertebral discs begin to degenerate and we shrink in height.
Hmmmm well I dunno about Your bones being closed or not Bro...but, I joined the Marines at 5'6 130lbs 18yo(to the day)...at 18yo & 6months was 5'7.5 140lbs(after bootcamp) & now am 5'9 200lbs...so I grew an extra 3 inches after 18...1.5 inches & 50+lbs coming from 19yo & after