What are your temperatures and what type of substrate are you using?
She can definitely take a bigger prey item, snakes are stretchy...most of them are made to take large prey... boids more so than others. A 2ft boa can easily be on small maybe even medium rats. I have an Irian Jaya carpet python that is just under 3ft long and taking medium rats... and he is a very slender snake compared to a heavy bodied boa.
It's my personal belief that redtail ssp. should not ever be fed a mouse in their life... from the time they are born most of them are big enough to eat pinky rats. and you say "regularly" how often do you feed?
If everything in your set up appears to be correct that I would venture to say that your snake is just always hungry because it is not being fed enough, thus is nippy and pissed off all that...cause it's hungry! Aren't you pissy when your hungry?
Also, snakes are not birds or mammals.. the thought process of putting her back is giving her what she wants does not really apply here, they don't learn in that way. However they DO become accustomed to handling through constant and gentle handling as suggested..however if she used to be ok with being handled and is now not it is not because she isn't used to it.
Another thing you might try. If she is in a glass tank, cover 3 of the 4 sides with an opaque material, this will make her feel safer and more enclosed since she doesn't like the hide for whatever reason