I wonder how long you have given it. I opened my shop in 2009 and it took a while to get seen. I promoted myself on social media, built up a good following which I continue to feed as best I can. I have good SEO so even if searches on Folksy no longer find a lot of my stuff, searches on Google always do.
But you must remember that there are an awful lot of shops out there on the web so opening a tiny little shop there is like opening a tiny B&M shop on a little side street in a giant city . If you did that you would surely send out flyers left right and centre to attract the customers in through your door as otherwise they will not notice you are there and will walk past.
It is just the same on line. You need to do what you can to get yourself out there. Once your shop is known then it will hopefully grow.
Repeat customers are fantastic. I have lots and I Always include business cards with everything I send out as if what I send is gifted that may well be another customer.
I note that your FB posts are just links to your items in your shop. You would be far far better to add some interesting text in its place and a directly uploaded photo and then put the url in the comment. That way FB will give you a far better reach for your posts. FB does not like you to use commercial terminology (unless you are paying for one of their ads in which case you need to). I Never use the words Shop or Order. I replace the alphabetic O with a numerical zero.
All this will apply just the same whether you are selling on Folksy or on your own website.