Ok, well I thought that my problem was fixed, but apparently I was wrong.

I recently was having trouble with no heat in my truck, which I found was caused by low coolant levels. I replaced a bad water pump, gaskets, and thermostat and then thought that I was good to go. Wrong! I have noticed over the past couple of weeks that my coolant level continues to drop. I have checked my hoses and the water pump gaskets, but I cannot find where it is going. I don't see any drips or any puddles on the driveway. I do detect the smell of burning coolant when the engine gets hot. I have checked my oil to see if it was showing up there because of a bad head gasket, but it looks normal. Does anyone else have any thoughts? Thanks for reading!