Weight loss tips?

Ok so im 5'6, around 175. I had a pretty strict workout regimen a while ago with school, but now i am at a different school. I have only gained about 15 pounds since may, but i want to find ways to lose more weight. I go up and down roughly 36 flights of stairs every day, and i dont have much of an appetite. Im not eating nearly as much as i used to, but i only seem to be gaining weight. And now all the things i am eating are healthy. I also tried the apple cider vinegar plan, but i couldnt keep that down. How can i lose the weight?