Welcome...I wish you every success. But you may find it easier to aim for a 2 year period for your 100 pound weight loss. Either way you still lose 100 pounds. Remember every person loses at a different rate. Women generally lose slower than men. Older folx lose slower than younger folx. The amount of exercise you get has a direct bearing on how much weight you lose.
Regardless, you will do fine. Follow your program and eat wisely and you will do fine.