Some good looking shots there, one or two a bit overexposed but that's being picky. A couple of general points on composition, the rule of thirds is a good way of framing a shot (
http://www.aea1.k12.ia.us/lois/ruleofthirds.html), don't be a slave to it but it does work.
You're also making the standard error of shooting everything from your standing eye level, get down on your knees, crouch or even lie flat for different perspectives. Looking at the images of Sasha, get down to the dogs eye level and see how much better the images can be.
DW (sorry for the rubbish quality, high ISO)