I had to read around about the Laaglander (yes, it's Dutch) DME when I brewed my stout. I used that brand of extract for almost of my fermentables (except a lb of brown sugar I also threw in). The gravity seemed to high.
Anyway, what I found when looking for help with this was that it was perfectly normal for your final gravity to be a full 10 to 15 points higher than the same recipe brewed with 'normal' extract.
Your target OG was 1.050.
You actually ended up with an OG of 1.062 (0.012 > target)
Your target FG was 1.011.
You are currently at 1.033 (0.022 > target)
I think you are done. Add 0.010 to the recipes estimated finaly gravity gravity due to using high dextrin DME, and add some more since you started with a gravity higher than the original recipe called for, and I think you are pretty much in range.
No harm in letting it sit longer, rousing yeast, or even pitching MORE yeast, but I personally think you are near the end of the fermentation road with this batch.
Ground Fault Brewing Co.