Don't use her as main DPS, use her as a sub "burst" dps support/healer. So basically, use her as a more usefull healer than Barbara.

She doesn't deal a lot of dmg as she's Geo so she can't create reaction (she has good base dmg though but still, she doesn't scale nearly as well in term of DPS compare to other element character) but what she's good at is creating some breathing room where Barbara might struggle (she's squishy and doesn't heal a lot without charge attack but using charge attack expose her at taking some potential dmg).

She's also quite good at clearing a bunch of trash mob and I think her heal heal is based on each ennemies hit, so when you get overwhelmed she can heal more than Barbara and still handle the situation easily because of her shield/Reaction shield (On top of not debuffing your character with a wet status)