Congratulations on making it this far. I went thru surgery and radiation about 2 years ago. The list of what tastes OK, as you already found out, gets pretty short. A couple ideas - try simple puddings such as vanilla or chocolate, green beans tasted normal all the way thru, french toast, pancakes, simple soups, soft bread with butter, jello. Try blending things with a vitamix or similar. I would dump an avacado, protien drink or mix, in with vanilla ice cream, bland fruit (mango, banana, etc) and milk/almond milk, to try and jam some calories in there.
Track your calories. Force the min 2,000/day. Stay active (walking, yoga, biking, etc) if you can. It will help your recovery. Food/flavors get worse all the way up to about 2 weeks after your last treatment. But, the good news is, it starts to get better after that. I am still finding foods nearly 2 years later that are returning. Most food taste good again.
Sending you prayers and good vibes.