your basically bowling a carrom ball from what i can tell, a doosra would be back of the hand, you seem to be bowling from the front of the hand.
if your length is a problem its because your not strong enough in your run up and with your grip. make sure you stand tall when you deliver and reduce the flight, eventually as you get stronger with practice your control will come. you also need to bowl the carrom ball slightly quicker as its primarily a stump to stump delivery, a lack of over spin means batsmen wont deceived in the flight, so giving it too much air will get you smacked against good batsmen.
any type of new spin delivery is hard to control the length of initially, just persevere and it will become easier.
hope that helps. and develop a regular offie too, or the carrom googly like kumble used to bowl.