My first time getting any orthodontist treatment

And I have a class 1 bite so he said I could’ve either went with top braces or retainers. I obviously picked the one that cost lower for the price and went with the retainers. I’ve never heard of retainers moving teeth but I guess my teeth aren’t that bad the only ones crooked are my front 2 teeth so maybe that’s why he recommended me them anybody else had this problem ?