Like everyone else with the goal of getting bigger, you need to eat for it. Too many people look around for the ideal workout program without giving the diet enough attention (growth will not happen if you aren't putting on weight...especially given your background). Shoot for around a pound extra a week, give or take some (1-2kg a month).
Start to introduce more foods into your diet and focus on protein/fats. Carbohydrates are easy to get in, but they fill you up too soon without getting in enough calories (not good for someone like yourself who's stomach likely has shrunk). Have your meals, then fill in the gaps with shakes (e.g. 3 meals a day plus 2 shakes in-between).
It may feel a little uncomfortable to start with (sickly), but if you do it gradually it'll be fine. As your stomach expands, and appetite increases (this happens when you start eating more quantity of food, more frequently), it will be easy to eat a reasonable amount of food for growth.
As for your training routine, don't get distracted by articles etc. Go by your own progress and needs. Progress is the key! If in a year, your bench press went from 6-8 reps at 60kgs, to 6-8 reps at 100kgs...guess what? Your chest/triceps/delts got bigger. So you need to train a muscle part as often as you can, making it stronger, without neglecting other bodyparts.
Start off by assessing how your body recovers. Most people can train a bodypart every 5-8 days (e.g. train chest on Monday, train it again on Fri...or for the less frequent trainees; train chest on Monday, train it again next Monday). Whichever plan allows you to recover and get stronger on for reps is the one to go with.
As for volume, a good middle-ground approach/starting point is to do 8-12 working sets per bodypart per week. E.g. 2-3 sets of flat bench press, 2-3 sets of incline bench press, done twice a week = 8-12 work sets for chest/week. Or for legs (which often takes longer to recover and more rest days between training), you may do 12 sets worth of training all in one session done once a week.