Thank you for your compliment. I really appreciate it. First off, I’d like to say there is nothing wrong with negative space and an incomplete feeling. To be honest, I tend to do the same.
What I think you should do is get a set of watercolors and some watercolor paper and gradually build on what you are already doing. Pastels might work, too. From the way you described your process, I think watercolor would fit nicely. Don’t try to control them. Just let them scatter, spread, and flow. Build up gradually. Continue to paint intuitively. Get everything out on the paper and feel good about it.
I’d love to see your sketches and what you come up with as you expand your style.