I have being feeding her extra mealworms, calci worms, bird seeds to boost protein intake, but she still shows no sign of re-growing her feathers back.
Go easy on the worms, and forget the bird seed totally.
What is her regular feed, with protein and calcium percentages?
Probably not molting.
Might be pre-broody.
Some birds pull feathers and have bare spots, never been a problem here where it's really cold, so no need to bring her inside. The feathers may not grow back until she molts at ~14-18 months, so don't panic.
Do not treat for bugs unless you
see them.
My Bug Check Notes:
Have you checked them over real well for mites and/or lice?
Google images of lice/mites and their eggs before the inspection so you'll know what you're looking for.
Part the feathers right down to the skin around vent, head/neck and under wings.
Best done well after dark with a strong flashlight/headlight, easier to 'catch' bird and also to check for the mites that live in structure and only come out at night to feed off roosting birds.
Wipe a white paper towel along the underside of roost to look for red smears(smashed well fed mites).
Good post about mite ID by Lady McCamley:
https://www.backyardchickens.com/threads/my-chicken-has-mites-now-what.1273674/page-2#post-20483008
Oh, and......
Where in this world are you located
@Lin_0330 ?
Climate, and time of year, is almost always a factor.
Please add your general geographical location to your profile.
It's easy to do, and then it's always there!