You have a great talent for drawing IMHO.
I would suggest you combine that talent with a little Photoshop magic (or any image program probably) and use a hard edge brush set to color mode to add color to your work with little effort. The attached image took about 15 minutes to color (hope you don't mind, just wanted to provide an example of the method.)
Color mode lets you paint an area with just the pixel color being changed leaving the artwork untouched for the most part. If you make a mistake just repaint in the color you messed up. It's a lot like coloring inside the lines. White areas don't pick up an color.
The color mode mostly allows for lighter colors but I use the overlay mode at a reduced flow to get darker colors. (Overlay at a reduced flow also adds some color to the white / pixel free areas as well)
Again, great work . . . =)