I would strongly advise against watermarked photos. Nothing is more annoying than trying to check out your art and there's a big obnoxious watermark across it blocking the view.
Think about it, your shop photos are only approx. 5x7 images at 72dpi. The few people who would copy them can't really do much at all with them. The kinds of people who buy art, buy it because they see value in it. The ones who steal it aren't going to decide it's worth something once you've watermarked it.
I think that you guys should consider reworking your titles and tags. Sure, maybe you're already getting a lot of traffic. But you're not getting sales because the right kind of traffic isn't finding you. You need to find the people that are your target market.
I know this is tough, I'm struggling a bit with it myself at the moment. Don't be discouraged, it takes time. And keep in mind, Jan - April is the slowest retail sales period of the year. There are less people buying now, but it will likely pick up over the next few months.
Getting back to reworking titles and tags, I would really recommend reading these articles:
https://www.etsy.com/blog/en/2011/putting-your-shop-on-top-etsy%E2%80%99s-most-relevant-search/http://ohmyhandmade.com/2011/contributors/etsy-relevancy-search-101/They've been a huge help to me. You all have great photos, so I hope the right buyers start finding you. One thing I would recommend is try adding dimensions of the work to your titles. Kimmie, a few of your listings don't have dimensions even in the description.
I would also recommend keeping them a little different from each other. That way you'll throw a bigger net and it's more likely your shop will be visited.
It's also worth noting that I had an exponential increase in traffic once I had more than 50 listings and I add more all the time. The more listings you have, again the better chance you have of being found.
A couple of you only have shipping options within the US as well. This is limiting the number of customers that can buy from you. Consider adding shipping options globally.
I hope this has been helpful. If you want any help with reworking titles/tags or anything else, please let me know. Tags can be tough sometimes because you're not sure what the customer would search for. One of the other teams I participate in has a thread where you would post a listing and the other people on the team come up with tags for it. It's a good way of getting a fresh perspective on your work. If you'd like that, just post a listing here and I'll try to come up with some tags for you.