Dress too formal for a wedding?

🎃🍂

I have never been to a wedding and I am not a very "fashionable" person but I am learning lol, but I was wondering if this dress is too formal for a wedding? I just was going to wear simple gold jewelry and small nude heels? The dress is a navy and not a black incase that helps any! I'm just not sure haha

Edit: it's next weekend so in September and will be in the evening