I've tried, going really gentle, one hole at a time, and she still gets snippy. In that moment where the strap goes up, she yanks her head up, ears back. Like I said, when I re-tighten in the arena, she's completely fine, so obviously it isn't a soreness issue. I've also tried standing near her girth and kind of playing with all the straps. Like, not in an annoying way, but just touching the saddle, patting her near her girth area, rubbing her, etc. Once I had a lot of time to tack up, so I took about 15 minutes, trying to get her to stop being girthy. Each time she would fuss, I would stop touching the girth and walk up to her face, until her ears perked forward again.
(*Note: My horse always has her ears forward. And like most horses, I can tell a lot of her mood. If her ears are back, she's either, listening, like undersaddle, or hearing something behind her. If they're flat back, she's mad).
Also, I should mention, that she doesn't take the bit too easily either. She won't fuss, but she just closes her teeth and won't open. It takes lots of coaxing to get the bit in. Now, I'm thinking, that probably the two are connected, because maybe she's telling me, I don't want to be ridden. But in the arena, she doesn't fuss at all. She's perfectly fine.
So what should I do? Thanks in advance!