Hello fellow sufferer!!
I can assure you that you are not alone- I started doing it age 11 and have done it since (I'm 42 now).
I can't grow my hair longer than 1 inch (I'm male BTW so it's not too hard
) but any longer and I'll start twirling away. I love it- it's not classed as self harm as the feeling is pleasurable (apparently) but I'll pull and pull until it just comes out. I used to keep the tufts as well way back when.
I've had several periods when I had 1/2 inch bald patches on my head due to it- easy solution for me is to just have a buzzcut skinhead, I've had it a few times to stop the habit. And strangely, if my hair isn't long enough to twirl/pull - and I know it isn't- I won't have the urge at all.
Also will pull at my eyebrows. Not as much, but I can and once started it ca be difficult to stop.
I've tried quitting several times, it's subconscious and lots of times I do it without even realising it (I've even done it in my sleep before- went to bed and woke up the next morning with a knot of hair at my fringe that wasn't there the night before)......
Short hair is the only solution for me I'm afraid!