Hi Molly,
Your art is awesome!! I do think coloring pages would be cool. BUT, I feel like you could easily get more sales if you do a couple things to your shop.
I know you didn't come here asking for a critique, but I really just think your art is so amazing that I think you could sell so much!!
One thing would be to add a LOT more items. I didn't start getting regular sales until I got up to over 200 items and had that amount for quite awhile.
Also, diversifying. You definitely have a nice variety of themes, like fruit, birdie, feather, cat, etc (which means you'll reach way more people because basically all the people that search for "fruit print", and "bird print", and "feather print", etc) - so if you basically just do this MORE (increasing your number of available items to over 200) then I believe it would help a lot.
Another great way to diversify is to offer different types of products. I KNOW you said you can't afford to build up your product line, but there are certain things you can buy that would be a very small investment to build up your products.
BUTTONS: You can get 25 buttons made from your artwork for only $5.00. And with the going rate of $1/button if you resell it on Etsy, you can basically pay for it by selling 5 buttons.
https://www.etsy.com/listing/161821697/25-1-inchOnly $5!!!
LUGGAGE TAGS: Only $18 for a 100 pack. Just print the picture from your own printer & slip it in. Sell it for about $4 per luggage tag.
http://www.clearbags.com/spec/vinyl/luggage-tagsGREETING CARDS: Buy 20 for $16 (80 cents each), resell for $2-4 or more.
http://www.overnightprints.com/greetingcardsI think those are very small investments, and they would expand your product line, resulting in more views from search and consequently more sales.
I think it's really important to offer products at ALL different price ranges, so that people who LOVE your art don't have to spend $17 on a print. Similarly, someone may WANT to spend a BUNCH, so try also doing sets of prints, and larger prints (you can print an 11x17 or 11x14 at Staples for $2 - sell for $25 or so).
I DO think it would be great to offer coloring pages, because that would be diversifying more. So I think you should go for it. But I think you should make other stuff too :)
Heather