Advice Traveling in Portugal with Seafood Allergies

Hello! Our family of 6 is so excited to travel to Lisbon, Algarve, and Porto in a month! I have a serious seafood allergy, and I’m a bit nervous about dining out. Are there specific restaurants or dishes I should avoid? Also, any tips on communicating allergies in Portuguese would be super helpful. Has anyone else traveled to Portugal with food allergies? What was your experience like? Thanks in advance!