Roy, you may have answered this, but I didn't see it. Is your stove still lighting & burning? Should be an easy way to tell if you still have propane.
As others have mentioned, you should have a tank gauge. Mine is on the tank & not easy to get to. I have to climb in the pass through compartment & remove the forward panel to see my tank & gauge.
I will tell ya that I have ran my furnace for up to 4 days before the darn cheap 2/3 light changes to 1/3. I really don't like those gauges.