Originally Answered: Good weight loss program?
First of all, you have no need to worry, as your weight for you height is in the healthy area of this chart http://www.nhs.uk/Livewell/healthy-living/Pages/height-weight-chart.aspx . So you are healthy and do have a potential for a better body. According to many formulas, taking your hight of 5'4 your ideal weight would be around 120 lbs, (ranging at 110-132 lbs). I'd say that is really possible. Until your school starts you have 46 days. If you have already started insanity routine, you shouldn't worry at all, that workout is really insane. But I would suggest to start running long distance everyday, I know it's hard, but if you really want to be in shape this is what it takes.
Start your first run tomorrow. Run as much as you can, do your best, make sure you're really tired and next day do the same distance but add 10% of a previous day. Keep increasing distance every day and I can guarantee you a perfect shape for 27th of August ;)
For a better result you can do sprints of like 50 yards in the end of the run, but trust me, it's very hard, if you ready to do that you'll notice difference very soon.
Oh yeah, make sure you drink loads of water. At least 9 cups a day! ;)