OMG! Sooooooooooooo cute!! She is starting to develop her mature coat - I remember that in between phase. Get ready...her legs are about to take over. Around 6 months old Huey's legs started getting long and he looked like a gawky teen. Still adorable but he was all legs for a few months until the rest of his body caught up.
I can see a goofy streak in her eyes. Huey had that same look and he was a total clown. Clownish but w/a little bit of ornery. Awwwwww.
If you didn't already have a mastiff, I would warn you to get plenty of rags handy but you're well-versed in drool. Or, as we used to call it...sloodgey.
Again, she's adorable.