I agree with HVAC and adjusting dampers(if you have them) or adjusting the registers in the other rooms is the first choice. The HVAC contractor may be able to speed the fan up to get more cfm flowing or he may need to just add another duct and register to your bedroom to get more air there.
You might also check to see if you have an air return in the bedroom. Every room with a register should have a return to get the air to flow round trip. If you have no return, you either need to add one or keep the door open. On mobile homes they just put returns through the door or leave a large air gap under the door for air to flow through. I seen houses with short cuts in the return system and especially in basements, they will put in air ducts but no returns and then you have to cut into existing ones or run new ones for all the rooms in the basement when you finish them. Good luck.