I thought you ladies might be interested to know I surpassed my 20% total loss this am! woop!
You should look at weight loss over a month not each week.Also scales may not be going down but you may be losing inches from the exercising.
I would walk faster than normal for a couple of mins then drop back to a steady pace then up it again.Do it every other day.
If you have a bike you could do that on the non treadmill days.