If you are willing to try offal and canned seafood, there's a wider variety of canned seafood than I ever noticed before. Recently I tried squid canned in its own ink. Wow, that was terrific! I've read that usually people aren't allergic to all seafood. You might only be allergic to crustaceans (shrimp, lobster) or you might only be allergic to molluscs (scallops, clams, squid). It doesn't sound like you're allergic to bony fish. If you haven't tried canned mackerel, it's very good. If you like smoked fish, kipper snacks are tasty.

If you can find the soup bones or neck bones, the meat might come off the bone filled with tendons and stuff. I used to throw that away but lately I've been eating it. I kind of like the crunch now. Head cheese is filled with ears and crunchy, too. I've kinda grown a taste for it. So offal can lead you to more and more new things if you are willing to explore.