Hrmmm,....She seems to be very honest which is a huge plus. It seems that you are the on that isnt saying wahts on your mind as much as she is. As soon as she told you she wanted to go back to just dating you pretty thought in your head that it was over, but you said nothing about what you wre thinking to her.
My advice( not that I know what I am doing either ) would be to tell her how much you like her, what you enjoy about her, that you dont want her seeing other people, and that its ok to be officially dating someone and STILL hang out with your friends without the SO being around. Is she not comfortable with dating someone and not seeing them for 2 days?