18 lbs in two weeks is a phenomenal rate of loss. Most of us lose 15-25 lbs in the entire first month. You are going to end up on the higher end of that range, if not over. You may be basing your expectations on what you see on shows like "My 600 lb Life". Yes, those people do drop a ton of weight the first month or two, but don't forget, they are starting out at 600+ lbs. For those of us more "normal" obese people, that much of a weight loss isn't at all common.. You will undoubtedly see a few of us who drop 30 lbs the first month, but they are outliers. Your weight loss is right on target - in fact, it's above average.
P.S. I *only* lost 16 lbs the first month (and that's in a month - not two weeks), and I lost over 200 lbs. Your commitment to your program is what makes the difference - not your rate of weight loss. But again, yours is absolutely fine.