My puppy was growing fast until about 9 months, the slowed considerably. So at 6-7 months she was eating 7+ cups if kibble per day. At 9 months that went down to 3 cups, and now at almost 12 months she's getting 2.5 cups.
Might you be feeding to large a portion at each meal? Judge the proper amount by the dog you're feeding. If you can't easily make out the first couple of ribs when she's standing broadside to you, she's eating too much. Also, when viewing her from above and behind you should see a distinct taper just before the hips.
It's not the size of the dog in the fight, it's the size of the fight in the dog. Mark Twain