is this right? (cooling system)

one my 01' gt, the temp gauge always reads at least 1/2 - 5/8 to the hot side, my cooling fan seems to come on almost everytime i'm not moving, and everytime i check the coolant it's low but i never find a spill or leak. any info?

read the post about engine blown think he having the same problems .... ask him if he ever found out what it was