Looks like a very happy dog! I love dogs.
Your likeness can be improved a bit, here is my suggestion on how to achieve it. First pick some part of the dog as a reference distance. In my example I will use an eye. Measure the distance of the eye using the measuring tool of your choice; paint brush, ruler, thumb etc. and then measure to the top of the head from the top of the eye, like so...
The top of the forehead is a little larger than one eye distance up. Lowering your forehead will do a lot to bring the likeness of this adorable pup.
Next, you've painted the dog looking straight on to you, which isn't the case in your reference photo. Her face is actually turned a bit in submission to the person photographing, even though she's excited to see you. By measuring the distance on one side to the other you can see how much smaller her left portion of her face is from her right side.
The rest of bringing the likeness can be obtained using these methods, find the base measuring size and then measure, down, over, up, whatever is needed. This method isn't exact, but will get you VERY close to your likeness.
Because she's lit by indirect light, the shadow pattern is a bit more difficult to tease out. You are pretty close, but if you look at the photo, you can see she's a bit brighter lit her right side than her left side. I turned it black and white and made it more contrasty to emphasize the difference.
Some areas of the face are pure white and are facing the brightest of the indirect light. So there are areas which are more in shadow as well. I would direct your attention to the sides of the muzzle - you may notice one side of the muzzle is lighter than the other... not by a lot, but it is there. Perhaps thinking of the lightness and darkness of your paint rather than the color - photograph your painting and change it to black and white to see if you're hitting the proper values for the color.
The shadowed area on the face are going to be the portions which aren't facing the bright indirect light...
You aren't too far off in the fur, it is a relatively short and smooth coat. There isn't a lot to do to make fur of this length, it is painting a short stroke of lighter color over a darker color in the direction the fur is growing. Don't blend it.
Love this picture, I will enjoy seeing what you do as you bring it to a finish.