Cotton on Green ~~ Finished?

I've worked on this piece and another one for several days. I had built the canvases quite some time ago and set them aside. At the time I had another, more pressing project. Oddly, I can't think of what that was. 

Nevertheless, I discovered the stack of canvas pieces and decided to load them on the long-arm before something else jumped in front of me. I have a few more canvases in the stack, but I want to see what the green background looks like. 

I've been working on this series of cotton paintings and have eight or ten pieces. I haven't really named any of them, but I think I'll just number them. Luckily, I've written about them and can look up the order. 

With this piece I was going for a cleaner, less is more, feeling. I'm not sure it's working. I keep thinking there's something missing. If you realize it, please let me know. I will definitely rework it. Otherwise, my plan is to show it to my artist friend and ask her opinion. She will be absolutely honest with me! And I believe strongly in the power of constructive criticism and learning from others.

Oh, I have to give credit to my sweet husband for building the frames! We've created a pretty good system: I sew the canvas in no particular size--just whatever works for me for the moment--then choose one when I'm ready to paint. Once the painting is complete and dry, I decide on the dimensions and ask for a frame. This one is 16" square. He builds it, I mount the painting, and voila! we have a painted quilt. Isn't he the best?!

Here's another picture so you can help me with a comment. I really want to figure out what I'm missing. Plus, some of the other painted quilts in this series.

You can find the posts for these paintings here: upper left blue, upper right neutral, lower left neutral, lower right blue.