Thank you so much! I’ll look into it and yes, I draw on a tablet. :)

@Fiona Brown  
Oh, so you mean that you draw on your phone or tablet?  
Well, I don’t know that app, so I can’t really guide you here, but maybe this video can help you out.

I use the Adobe Ideas app.

@Fiona Brown  
“Layer” in the sense of the layers that are common in graphic manipulation programs, like Photoshop or GIMP.  
I see here that you probably colored the areas using just the paint bucket tool, and this left some white pixels adjacent to the black lines, causing an annoying “feather effect” too.
 
There are programs that smartly fill the areas without these issues (mainly Photoshop), but if you don’t want to spend money on a hundreds-bucks license you can do well with other free alternatives like GIMP, and layers.  
Layers allow you to draw different parts of your drawing in different sheets that end up superimposed to form the whole picture. The trick here is to put the boundary lines on a layer, and the colors in a lower layer, so that the color seamlessly joins the boundary.
 
Consider this for example: >>855764 (merged)  
As you can see, the white pixels near the lines aren’t present there. That can be achieved with some little effort using layers.
 
Ask away if you have questions.  
What program did you use?

What kind of layers do you mean?

This is nice and funny!  
But you have to learn how to deal with layers, Fiona.

Oops I forgot the whiskers….LOL. I’ll fix that later. (: