I would pay the $300 and get a home energy advisor come and do an energy assessment of your house. There's definitely something wrong with the heating system in your place but it might not actually be the furnace. Your house may not be airtight or you might not have insulation installed properly.
The energy advisor will come and do some blower tests to check the air tightness of your building shell, test the insulation and your HVAC system. They can then give you a bunch of recommendations on what to do and what's going on.
Use the accredited advisors found on this page:
http://oee.nrcan.gc.ca/residential/p...t-advisors.cfm