How can I loose weight the healthy way in 2 months and a few weeks?

I'm 17, last year around august-december i could fit my boyfriend jeans that i bought from aeropostale, they werent tight around my waist or anything, they were very loose but didnt look baggy, well since the last 2 months,ive come to notice that i have to fight to button them up and when i have them on,they feel so tight that i feel like i cant bend over or just move without feeling comfortable, my stomach was flat but yet had a little pudge that wasnt very noticeable, how can i loose weight over the next 2 months before school starts back yet keep it off?