Don't forget that your weight will fluctuate with IF because you're depleting/ replenishing muscle glycogen so often. When you deplete glycogen you can lose a lot of water weight - this is why people who start diets always lose 10 pounds so quickly, then stall. Try to weigh yourself at the same situation only - say, at the end of your fast, for more valid comparisons.
One thing that surprised me about IF was how easily I've been gaining muscle. I haven't lost a lot of weight but I have visible abs for the first time in my life, so I must be losing fat. So the scale isn't always the best gauge of progress.