Gaining weight but still have so much to lose :(

Hi everyone, I've been losing weight for almost a year now and at my best have lost 60 pounds. At 5ft 3 and 17 years old, my goal weight is around 125-130 and I'm currently 148lbs.

For some reason over the last two months I've stuck at around the 146-149 stage, and I'm not sure why.

I was eating 1200 calories and burning anywhere between 150-200 calories three to four times a week and after not losing weight for a month, I decided to up my calories to 1300. Once I did this, the first week I weighed in I had lost around 1.5lbs, taking my grand total to 60lbs lost. However, the next week, after continuing with the exact same pattern, I had gained 2.5lbs! Since then it's been up and down but I can't seem to lose more weight than my current 148lbs Not sure why this is happening but any advice would be welcomed! I'm really disheartened at the moment!