If there are remaining cancer cells... then you need treatment. You definitely need a second opinion, and they need to do something. The body rarely - if ever - resolves cancer on it's own, you are 22 and this is too big a risk to take. (frankly if you were my son I would have smacked the chemo guy upside the head and made an appointment immediately with someone else. Of the three disciplines involved with this type of cancer chemo has the least effect it's really only used to soften up the tumor for radiation to do more damage, or to try and stabilize the tumor. This is something your rads guy should be looking at, or even your ENT.)

The next stop for cancer - particularly if it is present in the nodes - is the lungs. Once it reaches this stage it's a grim prognosis. Add this to the fact that you are young and have no precursors for this cancer - that's scary my friend (younger people tend to have a more aggressive form of it). I would not walk I would RUN to get another opinion. If you didn't have bilateral radiation initially then that should be the next recourse.

Hugs - I don't want to scare you but your chemo drs wait and see approach is terrifying.