Propane usage

[2007dura]

I have had the rig out 3 times since I bought it, 7 nights total. Had to use the heater 5 of those nights. On 2 of the nights it was low 30's, other nights 40-50's. I use space heaters during the day, no oven, used stove 1 time for about 10 minutes. I did run furnace while on the road for 1 1/2 hours. I have emptied one propane tank. Is this normal? I thought a tank would last longer.