I've been growing my hair for nearly eight years myself
It's pretty much stopped now, I think. Not had it cut (not even trimmed) in that time, and I haven't noticed it getting any longer in ages now...
I heard once that hair stops growing (or slows down) as it starts to get split ends...
Dunno how true it is, and it doesn't make any sense to me (how does the follicle know when the tip of the strand is split?).
Anyways, my hair grows really fast when it's short, then grows slower as it gets longer, and eventually stops growing (or seems to, at least).
I'll sometimes buzz my hair off to less than an inch for no particular reason (I blame it on manic depression episodes), and it will be back down to my elbows in about a year, year and a half.
That is as long as it will grow. It doesn't get any longer than that, no matter the length of time that passes.
Go figure. :shrug: