I think it's a trust thing. It also could just be the kind of traffic you're targeting on facebook. eg. it might not be 'high quality' traffic so not people with intent to buy. Have you advertised a lot on facebook? Are you experienced with it?
I like the clean, simplistic look of your site and although you have the payment badges on the product pages I think you need to add some security badges somewhere if possible (like SSL secure transactions etc).
I think you need an "About Us" page I couldn't see one anywhere just to introduce your business and people usually expect that on most website businesses. Especially as you don't have a phone number or business address. I can't see how people contact you either? You need a "Contact Us" page for customer service. Just go take a look at any big brand you'll see they do this with an About Us page and customer service etc. An FAQ page would be good too. Shipping costs is there any shipping times and costs page so people know how long they'll have to wait? I couldn't see one.
And pages like this: https://popsockethouse.com/products/top-diamond have no product description or specifications. I'm actually not familiar with the product you're selling (although I'm sure lots of people are) but again I wasn't really sure looking at it what it does, or anything like that other than it's something for mobiles. Having some lifestyle images (so people using them or adding more images of them on phones etc) will help people 'get' what they actually do and why they need it.
So yeah just a few suggestions I can think of off the top of my head. Also add to carts and then no sales etc is pretty common I wouldn't worry too much but I think an about us page, shipping info page, contact page, product descriptions, security badges, some reviews and some lifestyle photos would really help boost your store to people browsing it. I like the look of it though.
Best of luck!