The graph up above is from a patient of mine that I've been seeing since the fall of 2007 (for you Americans, the weight axis is in kg).
The fact that her loss is anything but a straight line is pretty damn normal because truly nothing in life is a straight line.
What's not normal, or at least what isn't common, is that year and a half segment from the fall of 2008 through the spring of 2010 where her weight pretty much stayed the same. Not that people's weights can't or don't stabilize, but rather that most folks who are trying to manage their weights tend to give up if the scale doesn't keep going down.
Of course had she given up back then she probably wouldn't have gone on to lose 50 more pounds and may well have regained the 35 or so she had lost before her weight first stabilized.
Weight loss is about embracing your own personal best. At the time she wasn't losing her job required a great deal of travel and consequently she was reliant on many more restaurant meals and far less organization in her dietary life. When that changed, she started to lose again.
If you look carefully at the graph you'll see a little uptick in her weight over this past holiday season. She's not sweating it. Her experience has taught her that if she tries decrease her intake too quickly, it'll lead her to binging and so instead she's cutting her calories back down a little bit at a time.
All this to say, and I've said it before, success is about consistency, embracing imperfection, and being proud of your best, where your best is the healthiest life that you can enjoy living, not the healthiest life that you can tolerate.
Her best, and yours, are great, and scales can't help you to determine what your best is.