As a cancer survivor 10 years clear age 21m how do i not freak out about weight loss especially when it's easily rationalized (smaller meals, working more often, fewer snacks?

It is quite understandable that you have concerns regarding your health over prior illness, however you've changed your diet and daily routine which is most likely the reason you've lost weight. It would help if you establish a relationship with a therapist who can guide you through these difficult times. All the best..

What was your baseline weight and how much did you lose? Unintended weight loss is generally a matter of concern. You may try to increase your intake of food to see if your weight will start increasing. If it does, it would rule out GI or other serious causes of weight loss. Wish you good health!