You don't have to sell "brand new" items for your item to appear. I did a search for your "one piece" pink floral bathing suit and could NOT find yours (found yours by searching "newly listed"). Then I realized that you didn't fill out "item specifics" specifying "one piece" bathing suit (search engines need this info). Also I would add word BATHING SUIT (two words) on your title line in addition to SWIMSUIT.
Another thing I noticed was a couple of "major bathing suit sellers" are spamming EBAY (by duplicate listing their items over and over again). They should be reported for "duplicate listings" which is against EBAY rules.
Your bathing suits and other items are adorable! But you might want to "pay extra" to promote your items (because your bathing suits are more expensive than others listed...customers may never see them). I stop looking after the first page or two.
