Sena, Jane is really cute. I love her hair and the bow. She has a wonderful air of innocence to her.
I do agree that some proportions may need to be worked with. Not because she needs to look more real, she looks adorable as is, but if you are planning on making a comic she may need to be drawn in different poses and angles to tell your story and as is, she seems difficult to pose. Using the drawing you have, try drawing her from the side, behind, walking, sitting and anything else you can think of. This will give you a better idea of how her cartoon body will move and will make it easier for you to draw when you get to drawing the actual comic. It may be that her proportions are perfect just the way they are, so long as you have a full understanding of how your character moves and can make your point and drawing obvious (ie: people can look at it and know instantly what's going on in the picture)
While you're doodling her, maybe practice how you will draw her different facial expressions. I would expect that she will be showing many different emotions throughout the comic; sad when the betta is not well due to bad conditions and relieved when the betta becomes healthy again once conditions improve and such.
And I'm done. No one would ever guess by reading this post that I studied animation would they? Nope, didn't think so. >.<