@ZipLine-- What are you planning to use the toe separators for? Do you need pedicure toe separators or separators for relaxation?
Silicone separators are actually the most flexible, so they are more likely to fit than solid plastic or foam ones. I'm guessing you bought separators that are a single piece with individual holes for the toes to go into.
You need to get separators where the holes for the toes have an open end. Or you need to get individual separators where each piece is placed separately between the toes. These can never be too small or too big, they will fit perfectly.