Hiya, my ds went through exactly this at around the same age, twiddling that turned into pulling, and yes he did the moving round the head thing too, ended up with a bald patch above one ear for a good few months. Glad you've had her checked, sounds like trichotillomania proper is different and rare at this age, this is more of a self soothing habit that's just got a bit much.
A few things that helped us:
Cut her hair shorter, harder to get a good grip on if there's less length. Didn't stop the twiddling but did stop the pulling out bit.
Gave him something else to hold in the same hand he twiddled with, a bit of ribbon or silky fabric works well, has to be something with a similar texture/feel to hair for it to actually compete.
Kept a closer eye on when it happened, for us it was always tiredness or boredom (in the car seat, before nap) so tried to catch it before he got to that point rather than stopping him mid pull.
Little soft mitten type things exist for this too if you want to physically make it harder, though ds refused to keep his on.
Honestly for us it was mostly a phase, tailed off on its own by about 2.5-3. Try not to make a big fuss when you catch her doing it as they do pick up on that and it can almost become more of a thing. Easier said than done I know when you're watching bald patches appear.
How much hair is she actually getting out, is it more twiddle/pull single strands or proper fistfuls? Might help others with advice too.