Okee, you've got anatomy almost down, but there are 3 things I am most concerned about. Follow teh numbers on the picture and read the corresponding point:
1. The thigh (although i did not draw perfectly lol) needs to be a little bigger and less curved, if you know what i mean.
2. the back needs to sort of cave down a bit and slope back up by the hindquarters.
3. This is hard to explain, so bear with me. Where the line that separates the butt and the tail, the tail most of the time doesnt overlap, unless its in a pose where it makes sense or has its tail curved, etc.. also, try to give your tail more shape, try not to keep it stiff :B
hope tis helps ouo