Nope, your dog is right on track.

I have a growth chart for the average large breed, and a puppy of 4-5 months is supposed to be around 33-40 pounds. My 5-month-old puppy who is supposed to be 60 pounds when full grown is also 33-ish pounds. Your pup is right on target. Remember, you want her to be lean, not chubby or overweight if that's what is required for her to fit the chart. Charts are simply guidelines!