I'm alergic to shrimp and lobster, can i eat oysters?

I know for a fact that I am alergic to shrimp and lobster (i know, my life sucks...), would that mean that i cant eat all sea food? Like most people, i really want what i cant have... sea food. Do you think it would be safe to try things like calimari, oysters, mussles, or scallops? (not sure if I spelled some of those correctly) I don't have health insurance co I cant go a do some expensive alergy blood testing.