Simple rule: if your teeth start to hurt after you've put the retainer in, you're not wearing it long enough. How long is "enough" depends on your disposition. Maybe you can even get a clear (thus invisible) retainer? That's what I had - unless you always grin like a cheshire cat, it really takes some staring to detect it at all. Just talk to your ortho.
BTW, there are lots and lots of adults wearing braces and retainers, especially in higher ed - might even be cool to be one of them! Kind of makes you stick out, which is not all that wrong at this level. Really!
