When a head gasket blows, one of three thins can happen:
1) Coolant get into the oil, evident by milky looking oil
2) Oil gets into the cooling system, and you know exactlly what that would look like
3) Coolant gets into the combustion chamber, i.e., one or more cylinders. In this case, if a lot of coolant leaks in, you will have steam coming out of your exhaust like you won't believe. However, if just a little coolant gets into one of the cylinders, you will only notice gradual coolant loss. You will keep topping off the coolant tank, but it will continue to disappear.
In case #3 you can inspect the spark plugs to try and determine which cylider(s) the coolant is leaking into. However, from your previous thread, we know your failure mode, if in fact a head gasket problem, is #2.
I am posting this only to enhance your understanding of head gasket related problems in hopes that you can navigate your way through these dire straights more effectively. Otherwise, I know by now, you're caught between a rock and a hard place.
Best of luck