Ladies I need your help please !!!

This evening I'll be attending a wedding for the first time . The bride is my SO older sister. ( both bride and groom have been previously married and both have older children ) so they are having the ceremony at their house ( which is huge and beautiful I may add ) on there front lawn. Anyway my question is , is this outfit I picked out appropriate to wear to such wedding? I know you aren't suppose to wear a white dress but didn't know the rules about the cardigan, and what about my sandals, do they need to be dressier?? Sorry, I'm probably over thinking this , I just don't want to show up to her wedding and stand out like a sore thumb. Any advice on the outfit I've posted would be greatly appreciated !