Bubble wrap on the windows is underrated, honestly. Not pretty, but it works in a pinch. I’ve seen folks use magnetic tape and vinyl sheets too—easier to take down if you’ve got pets or kids. If you ever do decide to upgrade, there are some decent storm window kits that don’t break the bank, but until then, sounds like you’re making the best of it.
Totally agree—bubble wrap isn’t glamorous, but it’s saved me a few winters, especially before I got around to replacing the old wood windows in the back room. I’ve tried the shrink film kits too, but honestly, the bubble wrap was way less fussy and didn’t peel off with condensation. Only thing is, it can look a bit odd from the street… but I’ll take odd over freezing. If you’ve got older windows, draft snakes at the sill help too—my grandmother swore by them. Sometimes it’s all about layering up solutions until you can do a proper fix.