It's not a secret mystic path. What you are doing is building your attention with this excercise. Basically building your brain. There is nothing secret or mystical about it, at least not at this type of level.
What you need to do is really push your training. Keep doing it with a candle for 20min a day since that helps to balance brain chemistry. But I would suggest that you bump your training and start doing both external and internal tratak. Focus on a external object like a fruit or toy. For internal just use a mental image like a soccer ball or anything. Push your training to 30min or an hour. Once you are feel good turn on the tv or put on some music, and try to train with the distraction. Words and music will create imagery in your mind and take your attention away, when this happens just go back to your focused image and keep holding it in place. Work up to 1 hour, or 2 or 3. Being completely 100 percent focused on what you are doing is the goal.
Your mind and brain are like muscles that can be strengthened, but only when you truly build them. You have been doing tratak for 6 months and have barely gone past 20min. Does a runner just stick to the same routine day in and out. No he pushes himself, he sprints, he lifts weights, he challenges himself. Same thing needs to be done with mind/ brain training.