I completely understand your frustration. I just checked my log, and this is my 12th day at the same weight, and I've been very good except for a taste of wine yesterday and an extra l&g. When I go back through my log, I've had at least 3 periods where I've stayed the same weight (+/- 1 pound) for 10 days.
When it gets hard and the scale goes up by a pound or even 2, here's what I tell myself. You absolutely CANNOT gain weight by eating only 800-900 calories per day and living a normal life. There are lots of internal changes going on inside your body as it loses weight, and sometimes, your body gets scared/nervous/PMS/obstinate, and it holds onto water. Inside, you're only losing .2-.5 pounds of fat/day, but you can gain or lose 2-4 pounds of water easy.
If I were in your place, I would not exercise right now. For some people, exercise seems to require an extra meal to balance out the demands and keep you from going in starvation. I'd work to get the basics going good: eat your MF meals, have a good L&G, eat on schedule and get solidly back into ketosis. You can still be active; you don't have to sit around watching tv all day, but I wouldn't do anything strenuous.
When you get hungry, drink an extra glass of water and distract yourself from food somehow. I play video games or clean the house or organize my drawers. Or I go window shopping. It's a great way to go walking and it passes the time.
Hang in there! I haven't seen a single person who stuck to the program and who didn't lose weight. It works. Have faith.