getting fit after twins-weight gain 50 lbs!!!

I'm a 37 yr old mother of an almost 3 year old and 3 month old twins. I've always been in shape, been able to eat whatever I wanted & however much I wanted. That is...until I had my first child. Then I had to cut back on portions a bit. Before him I was a size 2 bc of staying active, playing tennis and golf, and working out with a personal trainer. After having him, time to exercise gets shorter and it took me about a year to get back to a size 2-4. then of course a year later, I got pregnant with twins. I laughed when the doctor told me I'd gain 50 lbs, and then cried when I realized she wasn't joking. And sure enough, I gained 50lbs although it didn't really look like it. She said it helped I was already fit. 3 months later, I have 15 lbs left to lose to get to my original weight but even more than that I have to get my tone back and get rid of that tiny c-section belly that drives me crazy!!! I'm not a tiny person but rather 5' 4" & lean muscle normally. So....after waiting 6 weeks, I started exercising 6 days a week, and now going back to the gym. Time to kick it up a notch and buckle down even more on my calorie count which is why I joined this site. Good luck to me and well, all those moms who've just had babies!!! We're strong and can do it!