Have you tried to do a purchase on your own store?
What you can do is create a discount code. Maybe a 100% discount for yourself. and during checkout see if you have problems completing the check out process.
When the purchase come to your orders you can just archive it. So you do not have to order from your supplier. Run through the process for the first time. you may discover what may went wrong.
Are you using FB ads to market your product and/or store? I'd be happy to hear more about that. It seems that you're tackling the wrong audience, sometimes it's all about finding that ''golden'' niche with big spenders and the numbers will start rolling in.
Secondly, it's hard to convert a single-product website. You could potentially get away with it if it was a novelty item, such as a Halloween mask that everyone wanted, 2 days before Halloween. In your case, however, there's no particular ''high-demand'' for a LED light that you can attach to a shelf. Therefore, it would be best suited to have multiple items, complementing each other within the same domain.
Your store layout isn't the issue, I've seen far worse stores that are racking up thousands of dollars in sales per day. It's very modern-looking and done with fairly good taste. Work on your audience and you'll get there!
All the best,