Good News. You were right, it was turbulence problem in that room.
I was able to lift the vehicle to more than 15 mts. Not instantly but by slowing giving throttle to more than 50%. I dint crash it.
Initially, that is around 10 to 15% throttle, it was moving here and there but after 40% throttle, it took off with ease but correction ought to be given always in all the channels. What I feel is that, Since Im not expert in flying, im unable to control it precisely... I will update you more tomorrow morning after flying the vehicle.
Thank you Holtneil for supporting me with valuable inputs all the time.