It's normal to stall around that time. Your body is just playing catch up. It's so normal actually, I'm kind of surprised nobody warned you about it. Either search here or Google "The Dreaded Three Week Stall" and you will see it happens to 98% of us.
You're doing just fine. As a matter of fact, you're even a little ahead of the game with what you've lost so far. Keep doing what you're doing and the stall will pass.
