I get where you’re coming from with the ultrasonic cleaners—mine looked like something out of a sci-fi movie, but honestly, it’s more hype than help. I actually ditched mine after it started making the retainer smell weird (maybe I overdid it with the cleaning solution?). Now I just stick to a toothbrush and toothpaste, sometimes a bit of baking soda if things look sketchy.
About swapping out retainers, though... I’ve heard mixed things. My orthodontist was all about getting a new one every year or so, but my friend’s been using the same one for almost five years without issues. I guess it depends on how much wear and tear yours gets? Mine started getting those tiny hairline cracks around the edges after about 18 months, so I figured better safe than sorry. Not sure if I’m just paranoid or if my teeth grinding at night is the real culprit.
Anyway, two years seems pretty solid if it’s holding up. I’d just keep an eye out for any weird smells or if it starts feeling loose. Retainers are expensive enough—I’d rather not replace them unless I have to.