Q: What are the symptoms before one reaches samadhi, if any? How to know if I am progressing in the right direction? Thoughtlessness happens, nothingness happens. What after that?

A: Shweta, thoughtlessness is not a big deal and nothingness again is a state which comes and goes. What is Samadhi? Well, even if I give you all the symptoms of Samadhi, it will not help you because your mind would use those symptoms; and would again speculate and again fanaticise about those symptoms and sometimes with auto suggestiveness, you will begin to hallucinate that you are having those symptoms.
Things do not work like that, you cannot calculate. You cannot, so just learn to enjoy your dhyana and its really very difficult because all those people who think that they are doing dhyana are not doing dhyana. Dhyana is not something which you can do. No way, dhyana is something which happens to you and when it happens, it happens and when it does not happen, then you may follow your breath and inhale and exhale deeply or do a mantra or tratak or do pratyahar, but it may not necessarily take you to the stage of dhyana.

So I believe that you are yet to experience what real dhyana is and Samadhi is pretty far away.