1. I do not feel that correction pads really provide the relief a properly fitting saddle does. No idea how you can resolve that, unless you try for a custom saddle.
2. If you are scared (and I am, at times, terrified of my own horses, so I am not being critical), she knows this. She doesn’t know why, so she is reacting to your fear – if you, her goddess are afraid, she will be as well. I find St. John’s Wort helpful.
3. As to the bit, I am not familiar with that one and am too lazy to look it up. I ride both my Arabians in loose ring French link snaffles, and rely on my voice commands, legs and seat to bring them into a more appropriate state of mind. No matter how flighty they get (very – even “afraid” of the dirt), I can ride them with just a halter and lead, so long as we go no faster than a trot. I am struggling with the canter, because I think they are too fast.
3. Yes, the presence of other horses can be a distraction, but company is also comforting. Is there anyone with whom you could ride? Even have her ponied at first?
Mostly what you need to do is relax. She will then relax. It is much, much easier to say than do. If assistance is available, try riding her bareback on a longe line. Feel your body moving with hers and become part of her. A bareback pad might also be a good investment for trail riding. For no good reason I feel safer that way (or a saddle without using the irons), which makes absolutely no sense whatsoever.
I hope you can both resolve this, as there is nothing more frustrating. To keep her from being bored to tears in the round pen, work on lateral movements, serpentines, circles, etc. to keep her from thinking she knows what is going to happen and concentrate on what you are actually asking her to do.
It is never the horse's fault