If you eat 50g of carbs or below, you are in ketosis. If you measure ketosis with ketostix, they are not accurate because ketones left in the blood may be diluted too much when you drink as much as IP recommends.
You have lost 10 lbs, which is great. Most of this was glycogen and associated water, but still a part of it was fat. The way fat/muscle is measured by your coach is not accurate. You would need a more scientific measurement to determine body fat percentage. But if you stick with dieting, you are sure to loose fat. Take measurements and pics, they will tell the story.
As to slow loss and potential thyroid problems, yes. Very low carb diets can actually enhance thyroid problems. If you were hypothyroid before the diet, you may want to adjust medication (if you take some, that is). Otherwise, there are some links on the recent post:
http://www.3fatchicks.com/forum/weig...b-results.html