163 pounds - 150 pounds = 13 pounds of fat
13 pounds of fat * 3 500 kcal per pound of fat = 45 500 kcal
45 500 kcal / 240 days = 190 kcal / day
Scary how easy it is to gain weight!
If you google "testosterone" and "Basal Metabolic Rate", you will find that hypogonadism lowers BMR by several percent. 190 kcal / day is just under eight percent of your pre-surgery BMR (~2500 kcal / day), so it is likely that orchiectomy has caused your weight gain. Sorry to be depressing
As for me, I have been losing weight steadily since my surgery, but I am on estrogen which compensates for the loss of testosterone in maintaining BMR. Also, the surgery and estrogen have relieved my body image issues, which has made it easier for me to motivate myself to eat correctly and exercise.
Hope you get your weight back down soon.