Would like to lose 15.?

So, In 8th grade I was about 197 lbs. Crazy, I know. It's the summer after 10th and I am 150. I didn't do anything seriously trying to get that off. And I've been 150 for like 6 months. I have not been working out like I should be to get this off, but recently I finally understand how I need to eat, but it's still hard. I want to get 15 off before my Junior year, I have about 2 months, I'm not sure how possible that is. But if anyone has lost 15 in roughly that amount of time, I could really use some help, the scale won't budge off of 150. The reason I haven't lost in awhile is because I've only been trying to maintain the 150 because I tried for 3 months and got discouraged when that number would not lower. HELP ME. I would be forever grateful :) Thank you so much, sorry for rambling.