Have you asked your parents why they chose this name for you?
On the theory that your board name "Ms. Salinas" means you are of Hispanic ancestry, I would guess that Dassia is a respelling of Dasia, which
Jose Albaiges Olivart's
Diccionario de Nombres de Personas says is itself a variation of Dacia, the name of the province of the
Roman empire which is now Romania. If that's true, Dassia would have about the same derivation as
Daciana, a name which is included in the dictionary on this site.