Worried about my Skink

This is my REC, she is coming up to 9 months old but she seems very small for her age? She don’t seem to eat much, nor come into the open EVER.

I knew they were secretive however the main concern is weight and size. If she is under eating I can’t tell, the worm dish is always full and near her hide. The enclosure has the right heat and humidity so I’m a bit stuck! I’d rather see her chunky than too small!