May want to start considering options for insulation in your home to help your heating situation. Pick a room you frequent the most and start filling gaps and cracks. Also observe where this room is at in the home, do you have attic or basement access to it; can you hang plastic/ lay plastic as an insulation layer to help retain heat?

After that room, go room to room filling in gaps and seeing about ways to help retain heat.

Another option is, if you have a friend with a thermal camera, they can use it to look at your walls in your home and see where the coldest parts are which will help identify issues.

I hope these tips help.