It's not addiction as much as psychological dependency, since in the current situation not using it means weeks of anguish, and associations like that build fast. If she had free access to it, she might fall into pretty bad habits!
Looks like Myces is becoming more troll than fairy? Is that why she can't hibernate like the others?
The official explanation is that she is outgrowing some fairy traits. The gland that produces the hibernation hormone had a fixed size at birth and is now ridiculously small for the rest of her body. She'll also have to give up on flying eventually due to weight, but hopefully she can continue long enough to follow her friends through childhood.
her hair seems to be filling out even more now too.
And to think the story began on her wanting to trim it!