Hi, I was 27 at diagnosis last year and further along than you so I scored all four; surgery chemo rads and hormone therapy.
I’m fairly slim, I started at 65kg and finished treatment at 61kg. Everyone is different your appetite may or may not be affected, mine was and I was pretty selective at what I wanted to eat and could stomach, but they also give you steroid injections which are notorious for increasing appetite and gaining weight. I’m a nurse and have seen this many times, the “steroid puff” assoc with chemo. I didn’t get any of it but I wasn’t wasting away after chemo. You can increase calories into whatever you can stomach quite easy these days.
best wishes.