I also ordered the Shapely Secrets set, and I found that when I ate too little during the day, I'd stop losing weight, because that's what your body does when it thinks it's being starved. I tried something similar to you, having only yogurt for breakfast, fruit alone for lunch, and a tiny open-faced sandwich for dinner, and I wasn't losing weight. Then I tried what the program actually suggests, and I found eating more like 1200-1500 calories per day allowed my body to relax and work off the fat. It's about making smarter choices, not eating less.
Following the rules in the book don't tell you to eat that little. If you look at the examples of meals in the guide, it says for breakfast eat like six scrambled egg whites with cheese and mushrooms, an entire baked apple and wheat toast for only like 320 calories. Dinner, eat pasta with veggies and tomato sauce, steamed veggies, fruit salad, all the way up to like 600 calories. It's in the guide. Instead, eating only yogurt and granola, separately for breakfast and lunch, I'd be surprised if you were getting much more than 500 calories each day, and not many of the nutrients you need. You're making your body work against you because it feels like it is in danger.
So I have been on this program now, doing the exercises only once per day, for 4 months, and I have lost almost 50 pounds. It's counter-intuitive, but you have to eat more to lose weight. Just eat the right things.