SHORT answer: Retainers are needed and should be worn for a lifetime. The first thing I would do it put in that retainer. If it fits with out killing you wear it 24/7. If it kills, don't throw it away. Make an appt with your Ortho.
LONG answer: Even those born with perfect teeth, who...
Wow, I am sorry to hear of your situation, which doesn't seem right on many fronts. First of all, having your braces off when your bite is not correct was not proper treatment, and then having no orthodontist to take over your follow up treatment after braces is also not...
Teeth move when force is placed upon them by an outside source. That might be braces, aligners, headgear, or rubberbands. While the amount of movement is different in each patient, generally "if you wear them, your teeth will move" holds true with rubber bands for patients of all ages....