How long can you go without a retainer when I've had it for about a year and won't be able to wear it for another 3 days?

If you've been wearing your retainer consistently for about a year, going without it for three days should generally be manageable. However, individual experiences may vary, and some people might notice slight shifting of their teeth even over a short period. It's best to wear your retainer as soon as you can, and if you're concerned about any changes, consult your orthodontist for personalized advice.