What a cutie! At first glance I thought Shiba (try googling shiba inu/german shepherd mix, not sure how to add the photos.) She could also have multiple breeds in there as well, but Shiba is what jumped out at me. Could also be cattle dog-if she came from down south there are A LOT of cattle dog x GSDs that come into rescue (have fostered several that looked like her as young'ins.) We also had a ridgeback foster that looked similar. In terms of age, its always impossible to say for sure, but what are her teeth like? Any adult teeth in there? Around 3-4 months she'll start absorbing baby roots and losing her baby teeth. Incisors tend to go out and come in first. Around 4 months is when canines typically come out, and 6-8 months is when most of their baby teeth are shed. This is just a rough timeline-every puppy, and every breed, is different, but it can be a helpful guideline!