This is a member to member Board. The seller is very unlikely to see your request.
Go to the seller's feedback page.
On the right at the top is a link "Contact Seller"
You will need the listing number.
Since the seller is in China, you may need an even larger size than you think. The Chinese cannot understand how large North Americans are and tend to cut small in any case.
If the dress is already in the mail, there is nothing the seller can do.
When it arrives you could, in theory, return it for a larger size, but tracked return shipping would cost $40 or more. And you do need tracking.
BTW - on eBay anything less than 99% positive feedback is questionable. 97% is C-, maybe even a D.
Did you read the negative and neutral FB before ordering? You can do this by clicking on the neg or neutral number.
If the dress you receive is unsatisfactory, your best bet will be to resell it on eBay or locally through a free online classified service. Ask the seller if you can use her pictures, but make your own measurements for the reasons above.
