I totally agree re the water!

And I bet if you had a pair of those jazzy scales that measured muscle and water %'s and weight you would find that your muscle % was UP and your body fat % DOWN!

Also, in relation to the "plateau" thing..........I swear to goodness I have a "plateau" once a month, the week before AF in theory is due. Then the week after my AF should have appeared, the plateau breaks again.

How often are you weighing yourself? Maybe put the scales away for a few weeks and just focus on what you are doing........you sound like you have the food and the exercise thing down pat: well done! And just concentrate on that and the water and only weigh yourself once a month?