First off, this is super adorable! Your drawing could easily fit into a book! Also, in my opinion, I think your blooming adds to the playfulness and makes it more fun.
Water color is definitely a challenge. Something you might try is putting a VERY light coat of water on the area you are going to color first.
For example, say you go to color the little guy's collar:
Step One: Take a clean brush and put a light, quick coat of water on the area. It will dry quickly if you didn't put enough, and in that case just re-apply.
Step Two: Take an equal dip, maybe a slight bit more, of your color.
Step Three: When applying, make sure to start in the middlemost area you plan to color. That way if it starts to "bloom" you can catch it quick with a paper towel. Paper towels are your friend!
I hope that helps!