Eno gives the fluff and softness to the Dhokla, after our steamer is ready, ONLY THEN add Eno. It should be the last thing to be added before putting in the steamer.
The batter that we grind is thick, adjust water to make it to dropping consistency, not too thin and not too thick.
150 ml may seem like a lot of water, if you leave it for sometime, all the water will get absorbed. If you are going to consume it right away, you could use a little less.