You're looking for too much, too fast.
It's normal to lose a pretty big chunk right off the bat - it's mostly water weight at first anyway.
8 lbs in 2 weeks is simply not sustainable. It's normal that you might gain back a few lbs - especially if you ate something salty or if it's near your TOM or any of a million other reasons.
At your weight, 2 to 2.5 lbs a week ON AVERAGE is normal.
And when I say "on average" I mean just that. I mean that some weeks you may lose 5 lbs and other weeks you may lose nothing and other weeks you may even gain a few back.
That's the way it works. It's the results over the long term that count the most - not the day to day changes.