I agree with jim on the technical side. I think you’re so brave to keep at this, and you will be reward with success as long as you keep shooting. These bumps along the way will greatly help you later when a "real" problem arises. I mean, the more you can learn about light and flash, and how your camera works, the more likely you will be to make great images under less than ideal conditions. Stay at it! DO NOT GET DISCOURAGED!

Okay, here's a few simple thoughts. If I’m being to critical or my tone is harsh, please excuse my lack of class, and just tell me, so that I can improve my critique methods, I don’t want to sound mean but I also want to get to the point without having to treat you like you’re a glass slipper. . .

(I know animals and people together are hard to shoot, so with that in mind, I have the flowing comments)

1. I think you need to focus more on the subject of the shot. For example, is it the interaction between the girl and the dog, is it the dog, is it the girl, I get the sense that you’re trying to captor the intimacy between the two, but sometimes it feels like they are documentary shots? Or are you trying to highlight the dogs win? If so, you need more dog and less person. I’ve posted a crop to give you some idea of how I would focus. The crop is the best I could do given what you posted, but you get the idea. This does not mean you can’t, or should not shoot whatever you like, it is meant to give you an idea of how to really focus on the subject, you have to really put your heart, mined and spirit behind that canon when you shoot people. If you think about it this way, you will get better results, and you will feel better at the end of the day... . I think the interactive or intimacy or relationship shots need more emotion and more interaction. Think of yourself as a candid, or photo journalistic photographer just capturing those moments between the dog and the dogs partner.
2. try a few portrait shots,
3. put your subject off center in the landscape orientation, or at least crop those shots so that there's is more balance,
4. watch your background! - use those branches or get them all the way out of the frame, in the second to the last shot they look accidental, and the background is distracting

Keep at it!!! Piece