Your Dress:

Proposal:
"You wanna get married? That's not crazy is it?"
"It's kinda crazy but.....Sure, why not?"

"I love you."
"I love you too."

Your ring:

Venue:

You (secretly) got married in the Room Of Requirement.

Wedding Invitations:
You didn't have any, you just told the Marauders and Lily.

Wedding Cake:

Lily and James just took some cupcakes from the kitchens of Hogwarts.

Honeymoon Destination:
You didn't have one, you just spent time together and with your friends because that was your happy place.