Are you ready to play it well? Probably not. Does that mean you shouldn't try it? Not necessarily.
I tried a similar stretch this semester. At my level, well, it was a stretch, I wouldn't try it at your level. My teacher assigned me Chopin's Scherzo No. 2. So, I worked really hard, and at the end, no, I couldn't do it. I couldn't maintain tempo throughout, and my left hand wasn't ready for the fast arpeggios. Did this experience do harm? Probably not. I will continue to progress as a pianist, and eventually I will reach the level where I can play it, and I hope to make a good rendition of it. Did I learn anything from it? I learned about direction in dynamics; even, fast fingerwork; memorization of a large work; the essential importance of a metronome; pacing; voicing; tension; and a host of other skills that have improved from working on that piece. The point is that sometimes we need to work towards a challenge that we cannot attain, because there is still some good that comes of it. However, I was also working on several other pieces at the same time within my reach. This Scherzo was not the focus of my studies.
However, your teacher did say that you're not ready. You should trust her. After all, you are paying her to teach you, right? If you're itching for a new piece, tell her and ask if she can play several pieces that you can handle so you can choose one you like. I personally believe we should all have at least one "dessert piece" at a time (My next one is Ravel's Valses Nobles, YAY!) to motivate us to achieve more than we would normally. However, this piece should not frustrate and defeat us, and your teacher is the only one in a position to determine whether or not a piece will do that to you.