I do a lot of energy audits for Harrisonburg Electric Commission, they offer them free to their customers. The problems I find in most houses are very similar and are caused by lack of building science understanding. Air leaks are the biggest source of comfort issues and wasted energy for heating and cooling. You can find air leaks in your thermal envelope by looking at fiberglass insulation.
Find places where your pink fiberglass is black and this is an air leak.
This yellow insulation shows air moving through the wall from an unconditioned attic into a conditioned space. Stop the leaks and you will improve comfort and reduce wasted energy.