In my humble opinion, I think the only thing that makes the twirling a problem is that it bothers you. I'm certainly not trying to invalidate how you are feeling. I just want to express that I don't personally think there is anything wrong with it.

I have a relative who twirls her hair and I've never really thought much of it. Sometimes we mimic her just to tease her a bit. But she doesn't think anything of it. She says it soothes her. And you know what? There are a WHOLE LOT of worse things a person could do to self-soothe.

Do you think maybe it soothes you too? Maybe you could find something else to take it's place. Like those little gel filled balls, for example? Those are great for keeping the hand occupied.