Been losing coolant not overheating

What to do is this. You need to pressure test the system. You need a colling system pressure pump which is nothing more than a hand held pump that screws onto where the radiator cap is. When the engine is cold, remove the radiator cap and install the pump. Pressurize the system and check for leaks. Another tool you can use is a dye for the system. It mixes with the coolant and after driving, you check it with a black light. The dye will glow. It makes things much easier to locate.

As far as bleeding the system, that shouldn't be a problem unless you emptied the system reciently or it got extremely low on coolant. If there is no port to bleed it from, I always bleed from the return hose from the heater core.