OP, as others have suggested, electric heat is very expensive to heat with.

When it’s 10 degrees outside, you have have your heat set to 65 degrees, you have a 55 degree differential. Bumping it up to 70 degrees inside and you have a 60 degree differential. The point is that the difference between 65 and 70 set point is not that much different compared to the 10 degrees outside. EPA says generally lowering the thermostat by 1 degree is roughly a 1% savings in electric bill.