Raising a multilingual baby?

Hi everyone! I'm going to be first time mum and I am just now realizing that it might be difficult to teach our baby both of our cultures. I am a Spanish speaker and he is Polish. We both want the baby to grow up knowing Polish and being proud like he is of his culture and knowing Spanish and being proud like me of my culture. I don't necessarily know how we would do this without one language being more dominant. It makes me sad to think that it would be mine that gets tossed aside. I feel like Polish will be more dominant because the Spanish speaking majority of my family lives in different countries and my siblings that the baby will be around the most don't speak Spanish at all! (Their dad is American. I barely speak Spanish with mi mamá because she's forgetting it. My dad is really the only one who was adamant about speaking Spanish but they weren't together.) I just want to know any tips?

SO's family all speak Polish fluently like him (he is first generation) and there is Polish school where we live in Chicago. Help me please 😅 I'm so worried.