Is my metabolism slower after that?

Hello everyone,

Alright so a year ago I started eating around 1200 a day to lose weight (healthy food mostly) and have kept it since then. I reached my goal weight, but then I had to eat the same amount of calories to maintain it. I tried to eat like 1600-1700 cals a day, and I think I gained a little, even though I'm not sure about it.
So, is it a possible that my metabolism is slower because of this schedule?

Note that my age is 15 years, height is 5'7'', and weight is 122 lbs.