I am considering buying a queen-sized Tencel sheet set from West Elm. As they do not have any reviews on the site it is very difficult to know how the fitted sheet will fit my mattress. The description of the fitted sheet is up to 16 inch. My mattress is 11 inch. As it will be difficult/a hassle to return, can anyone share their experience of the fitted sheet in the set? I would prefer that the fitted sheet does not slip and slide all over the place!