Congratulations on your weight loss. In January, I started an Optifast plan, which consists of 12 weeks of optifast and water only. I lost 25 lbs the first week, and since then Its been much slower. One week, I only lost 1.5 lbs. I wondered why I am depriving myself so much just for 1.5 lbs. I didn't give up. I decided just to keep going and now, this week (7th week), I have had a pretty good drop of weight.
I certainly didn't get fat overnight and I don't expect to lose it as fast as I once could. I do understand your disappointment, however. Sometimes not looking at the scale at result time can help too.
Bless you in your effort to get healthy.