5'9 at 17 could i still grow to 6'6?!

Yes, it's very possible.
There was Dennis Rodman who was 5'11" at the age of 19 but guess what, he grew!!!
In fact, he grew about 7 inches in one year.
George Erving another basketball player was 5'8" his junior year, but when he came back his senior year he was 6'3". He ended up being 6'6".
Look, is it likely you'll grow. Here it is:
Ask your relatives if they have had late growth spurts(you know when they were 18-20 years old) and if they did, then it's very likely. If not, well then it's not likely.
If someone tells you your growth plates have closed and can't grow no more, then they are misinformed, you can still grow, remember alot of your skeleton is still cartilage even at the age of 20.

Common Sense, and Bio class

i highly doubt it. that would be a massive growth spurt if you did
you probably will still grow a little bit more but not much

no!
your gens are not ment for u to grow that tall!

max is 6"2

Haha no