I really like the way this headed- I think it’s quite a charming character/piece! (if you’re still working on it:D) maybe try adding an extra light to the front left (towards) her to give bit of extra pop( not too bright). Apart from the rim, the lighting seems teeny bit consistent everywhere. This extra light could help with the hair, if you add a mix of sharp/blurred greyish glossy that presents where this directional light hits it. I.e. the front parts of the hair will be a bit brighter…actually the 'plastic version shader ’ would pretty much be it. Mix the two: mostly what you have with the current shader settings mixed with the more plastic version where the extra light hits it.
Also, maybe mix with translucency color slightly around rim outline of hair (with fresnel)? The extra light might help bring out the cheeks and forehead bit brighter too.
Hope that might help and hope you’re still working on it:D