Bella Thorne Says Hey Bra, I'm Back in L.A. (PHOTO)

Bella Thorne double cupped it at a pool party in L.A. Sunday, and speaking of cups ...

The 19-year-old showed Scott Disick what he was missing in a lace bra and Moschino undies.

As you know, she bailed on Disick after just one day in Cannes. She seems to be on a mission ... posting videos of herself ... showing off her body.

She's been everywhere in L.A. since returning from the Film Festival ... including with her ex bf, Gregg Sulkin. Clearly she's trying to make the point -- she don't care.