My nose has been congested so it’s really hard for me to breathe. Are there any safe medications I can take while I’m nursing?

I'd make my own "steamer" whenever I have stuffy nose during the winter. Pretty much just me draping a warm cloth over my head and inhaling steam from hot water. Sometimes I'd add some essential oils to the water like peppermint or lemon grass. Works like a dream and it should be safe enough to be used by pregnant women. Alternatively you can just turn on the hot shower and wait for the bathroom to steam up.