Wedding Dress

I have a size 8 wedding dress bought at david bridal in 2008. I don`t have the reciept, but I have the original 1st bill from when I bought it. I never wore it, I tried it one twice, when I first bought it and then the day before my wedding. When I tried it on the day before my wedding it didnt fit anymore (after 3 months of buying it) then i had to go out that night and get a new one. Tried to take it back to Davids Bridal, but they would not take it, Been trying to sell it ever since...I Live In Kenmore Wa