The 2x daily exercise sounds a bit like the crash diet - you'll do it for a period of time and lose some weight, then burn out, stop altogether, and put some of the weight back on. For both exercise and diet, it would be better to develop routines which are sustainable long-term. What good would losing 30 lbs do if you didn't develop the habits needed to keep the weight off? I also agree with Kara that you'll need to do strength work of some sort, rather than cardio only, to keep from losing muscle as you lose weight. Having more muscle means you burn more calories even at rest, so you definitely want to keep the muscle you've got.
If I were you (and I'm not, so take what works for best for you) I would aim to eat 1200-1500 calories per day and exercise 1x daily 5-6 days per week, with a mix of cardio and strength training, and aim to eat a minimum of 60g of protein per day (70 or 80g per day would be even better). That's essentially what I've done throughout my weight loss, and in doing so I have developed healthy, sustainable eating and exercise habits, I have maintained my muscle mass, am I am still losing weight at a good pace now that I'm at a lower weight that is similar to your own.
As Kara said, losing 30 lbs in 60 days is unrealistic, so expect to see something more like 1.5-2 lbs/week at the start. I'll also mention that while a weight of 115 is a fine target, I think 105 is too low. By BMI standards, it is nearly underweight for someone your height.
Good luck, and I wish you the best.
Began weight loss ~ January 18, 2011 at 280 lbs
Met original goal ~ Normal BMI (147 lbs) on March 8, 2012 Goal story and photos
Met revised goal ~ 135 lbs on May 12, 2012
Pregnancy May 2012 - January 2013
Post-preg weight loss ~ January 2013 - July 2014
Now maintaining < 135 lbs
Last edited by chickadee32 : 01-08-2012 at 10:23 PM.