I believe the healing ability is only for the other chick you've met at the bar. I forgot her name. I never know Jenna could heal. So... Yeah... Or maybe the dev add new ability to jenna that heals? Idk... Yet.
Maybe I'm just blind to it, but it seems I can only heal Jenna with the healing items. And since the enemies kill the other chick really fast, it's a "bit" annoying to be outnumbered in every fight. I know there's that skip mode, but using it to win the fights won't progress the quest.