Had similar struggles as you had(didn't take drugs though to eat more). 186cm and 60kg(~80 now) and was skinny for quite a long time and couldn't really gain any weight.

I did some convict conditioning and with the 2 extra meals per day(about 800-1000 calories), I could finally gain like 7-8 kgs instantly in the first month. In hindsight, 2 was too much. Try 1 extra healthy meal (protein + good fat + good carbs) every single day with some weight lifting or body weight training for a month and I'm sure you will see a difference.

It could even be a steemfit series.