The calcium and phosphorus levels in the Fromm food are fine. As for the AAFCO guideline, I would not be comfortable feeding a GSD puppy (or any other large breed puppy) a food with 1.8% calcium.
I prefer to stick to 3 meals a day as long as you are able, and the puppy is interested in all 3 meals. Omen, who will be 9 months in about 2 weeks, fairly recently lost interest in eating lunch and was switched to 2 meals a day. Jazz, my 6 year old, was switched from 3 to 2 meals at around the same age, if I remember correctly.
Omen v Wolfstraum
Jasmine Katie v Doolanshaus