Stalled
How awesome -- 33 pounds gone before surgery! It's a big head start, no?
As everyone else has pointed out, periodic stalls are normal. Our bodies have a lot of catching up to do when we're changing shape, and actual poundage lost is just part of it. There are also "stalls" dependent on women's monthly cycles because of water retention.
Someone else had pointed out in another thread that a good way to shoot past a stall is to do a change-up on activity and diet -- try some speed work in your exercise (1 minute of incredibly intense activity, then a few minutes of slowed activity until your heartbeat's back to normal, then another minute of intensity, etc.); make some changes to the food staples you're relying on, etc.
You've done a great job so far and you can trust that the trend will persist!