Good luck to you Ambra, wishing the best possible outcome. My two cents is that I'm about the same size as you, and never eat a lot. After I found out I was going to need radiation, I put a PEG in early! It made all the difference in the world. I just could not eat, and was wasting away, got down til 102. That was it for me! Now I'm a plump 110 and in my second week of radiation. Everything is scary, but there are a ton of us here to listen, encourage, and educate you. (I'm not one of the educators, but I can be your encourager and help comfort you in your down times)
Best wishes til next time...

Nancy (53 at dx)
Metastatic SCC. Stage III. HPV positive with occult primary. N1, no ecs
7/1/11 - L-Selective neck dissection. Tonsillectomy. All clean. No rad, no chemo.
5/29/13 - Found primary
7/3/13 - TORS
7/8/13 - Emergency Surgery/Blood vessel burst in throat
8/9/13 - Peg in
9/3/13 - Radiation starts 30 IMRT, 60gy BOT, 56gy both sides of neck
10/14/13 - Radiation ended!
11/12/13 - PEG out!