I'm no weight loss expert... but almost 20 lbs. in two months should be acceptable considering that losing 2lbs. per week is "safe" weight loss. Now keeping in mind that you don't weight that much to begin with, you're really going to have to dedicate yourself, it's definitely going to be a challenge.
Now just dropping in my two cents in if you don't mind
You may want to rethink the reason why you want to lose weight. I fully understand wanting to look good for someone... but to ensure that you are successful in your weight loss endeavor you should do it for you, no one else. If he likes you, he'll think you're beautiful even if you do have a little extraness