Hi There,
There is not a terrific difference between the MF 55's and the MF 70's.
The 55's have 11g of protein and 90 calories. The 70's 14g protein, 100 calories. So, if you use three shakes each day you'll be getting 30 more calories and 9 more grams of protein using the 70's. We generally have men and active women use the 70's because of the extra protein. Actually soy is a natural appetite suppressant so you're just getting a little more. That can be a good thing

You should be fine -- everything is so low in calories that the 30 extra most likely won't affect anything. And remember you aren't changing the balance. Next time unless you are a very active lady just order the 55's.
jan