First, You need to learn to write your posts as questions. To me, (and many others) you came across as a smart ars new EMT that learned all there is to know, in EMT class. I know that sounds harsh, but that is how your posts sound.
You can learn a lot from the people here, that have years and decades of experience. Most of us were doing EMS before you were born. We have seen these situations over and over again.
We are trying to tell you that a NRB at 15 lpm is not a justified treatment for this pt. You have a female pt that was forcibly raped. She is scared and anxious. Placing a confining mask over her face is not going to help her. It will make her anxiety worse.
As you learned in class( I hope), hyperventilation leads to inadequate gas exchange. The pt is unable to blow off Co2 and is retaining O2. Placing her on high flow O2 is not going to help her blow off Co2. Yes, some people will calm down some, with O2. But, I have seen them pass out from the same treatment. This is not what the pt needs at this time.
The best thing you can do for her is let her calm down. Talk to her in a calming voice. Do not ask questions of the event. Just use a little empathy. This can be one of the hardest parts of the job, but it is a part of it. You learn how to deal with a pt like this over time and from advice from people that have been there all ready. Go to your larger ED and talk with the sexual assault RN, they can give you advice on how to best deal with the Pt's.
So, don't be cocky, don't be a smart ars and ask all the questions you want. These people are on this forum to offer advice to the noobs. Hopefully to help you become a great professional.