It is hard to tell her size with her laying the way she is. She must have been abused at some point by a man, as dogs that act skittish like this with a particular gender often are. While you did not ask for opinions there, I do deal a lot with abused dogs, and I would suggest you spend some time with her, feeding her, going for walks and letting her know you are not going to hurt her. A dog may forget the person who hurt them, but they do not forget the hurt and will associate it with something. In this case, your gender. You sound as though you care about the dog and have had her so long. ... I just wanted to offer the advice, even though it may not have been asked for.
She is a beautiful girl. I tend to look at all aspects of the dog when trying to determine the various breeds that are there. It looks as though her legs may be short and her body long ... that as well as the shape of her face looks like there is Pembroke Welsh Corgi there. The ears would suggest maybe some Beagle even, though I am not as sure on that one. Seeing her size would help a little more, but I do not see any coyote there. The bark would more confirm some kind of hound. I will post a couple links of a Corgi Beagle Mix:
http://www.externsonthehill.com/wp-content/uploads/2008/08/phoebe.jpg
http://www.feelingismutual.com/wedding/snowfiona.jpg
Beagles come in two sizes, but neither are very large, and the PW Corgi is a smaller dog, so if your dog is over about 25 pounds, I would suggest there is a mix of something else there as well. But I would guess that anyway. I honestly do not see any "Staffie or "Pit" there. I could be wrong of course and have been before, but usually there is a wider head with that mix and I do not see any signs of that here.
Lab? Maybe. But I have also learned that most dogs tend to get dubbed as having "Lab" in them, simply because that is a popular breed and, to be honest, too few people spay and neuter. Thus a lot of Labs tend to "hound" about.
I may be totally off base with what I am seeing, but trying to judge the size of the dogs legs and the way her sweet little face is ... I see Corgi definitely with possibly Beagle or another hound mix.Maybe even Corgi and Fox Hound Mix:
http://photos-g.ak.fbcdn.net/hphotos-ak-ash1/hs472.ash1/25892_104531902903713_100000407123192_114125_7205711_s.jpg
That would explain a larger sized dog.
I hope this helped. And I hope your girl can find a way to open up to you better. I know it can be hard on a guy when he is not home as much as the girls and there is a rescue dog there that was abused by someone else. But she is a definite sweetie.
Oh...and here is a good picture of a coydog:
http://indigomtn.org/html/coy1.html