In my experience stress is "rocket fuel" for depression.

You are going through something that is very stressful, a huge life change, and trying to make your wedding day the "perfect day"

I know this will be hard but cut yourself some slack, you don't have to plan the perfect wedding, if this is the man you love and the one you want to spend the rest of your life with, then so what if everything at the wedding doesn't come off perfectly. You will be married to the perfect guy (OK nobody's perfect but you know what I'm trying to say) don't let others bring you down. Do what you can, and realize that at the end of the day it will be more than good enough.