Aw plum *hug*. I know how you feel cos that was me on SW - I just sts most weeks and mentally I was a bit overwhelmed by it. I stopped SW, ate whatever, and then gained 3 stone back in a flash!
You've still lost, albeit not the bigger loss you deserved. But I guess our bodies at some point must second guess us and slow it all down. Is there anything you could change? Your pattern of shakes/bars? Your water intake? Exercise? Flavours? Try doing one thing different and see if it helps in anyway.
I'm expecting a rubbish week this week as I'm bloated beyond belief on anti-biotics and a stupid pickled cucumber lapse. It's hard to accept when you are trying so hard!
Keep going girl. You've come a long way xx