Whats wrong with my honda?

I have a 97 honda accord special edition with a 2.2l sohc. It is not a vtec. My problem is that my radiator will not keep water and my car will overheat. I am fairly certain my radiator is not leaking, because there are never any puddles underneath. I can only get about an hours drive before having to refil the radiator. I do belive that the water is being burnt through my motor, but my oil is relatively at the same level and hasn't changed color much or texture. When I open the oil cap after driving, a small bit of white smoke does rise, which I ume is water, but there isn't anything coming from my tailpipe indicating the later. I was thinking it may be a blown head gasket. Does anyone have some better insight as to what it may be? Im somewhat mechanically inclined but a head gasket is a bit complex. An estimation on how much a shop fix would cost would be amazing as well.