Hi there the numbers are scary - but remember you are not alone and a lot of us are a few years out and doing ok. Chances are that the cancer was in the nodes before your original surgery. Often this cancer seeds to the nodes but sits dormant until the primary is removed then they become active, so your story is more common than unusual. Most ENTs remove a selective grouping of nodes when they are removing the primary tumor - this is preventative with this type of cancer. (Non HPV) but that is up to the discretion and experience of the ENT.
Bottom line is you are done, you got through radiation and chemo, and now you are healing - try to focus on that. Your scan will come soon enough and I know when faced with this we all want assurances and definitives but sadly this is one of the mental games the C word plays with you. It really just reinforces the reality all of us live by - there are no guarantees in life. Tr to put the fear aside - acknowledge it then ask yourself have I done all I can do at this point to fight this? (You did treatment - you followed your drs advice) if the answer is yes then focus on healing and living your life. Everyday people leave their home intending to return that evening and don't make it back - car accident? Shooting? All we have is now - so don't let the cancer steal your joy and live your life. Give it it's due attention - take your meds - see your drs. Go for scans but then do what you can to move on. Hugs...