I fixed it!! I tried out a solution posted here where I set the elements that were meant to appear above the sticky footer to sticky as well, but left the settings as auto.
At first it only fixed one of the three sections, then I realized the other two sections had erroneous classes leftover on them from the template that I had very heavily modified… whoops. It worked after I removed those. I feel a little dumb, haha, but I’m glad I figured it out eventually!