Having failed CFA level 2 with Schweser I am thinking of trying out Elan or Stalla and was wondering which had better item sets. I found out that Scheweser Practice Exams for the recently ended level 2 are not adequate enough. The style is different and it makes me feel uncomfortable when I was attempting the actual exam. It was so bad and my score for that section proves it. I did much better on the FRA/Corporate Finance and Ethics because I did the eoc questions to death. However, there wasn’t enough vignette style eoc on equity, derivatives and fixed income and there is where I failed miserably when depending solely on schweser.
Sad to hear your result…
I think most of us (ok many of us) had a tough time understanding the derivatives PM session this time. I too got a score of less than 50. I also found there are not many practise questions available as your rightly said for derivatives.
I used Finquiz, even it didnt have too many Itemset questions for derivatives. But i found them very very good for the rest. Analystnotes is another one which you can try and you get to read the material free anyway as well.
I never liked schweser style and never used them… May be you could give the above two sources a try… If you search a bit on the net, there are many many sites which offer free questions, Just dont miss them. I had many many such sites, let me see if I can get the URLs from my desktop sometime this week and share it. Meanwhile these two sites below are you must be aware, just in case you didnt 
finquiz is offering 60% discount for retakers and full time students. Email them at info@finquiz.com for details. I used their material and passed the exam. Was also having Schweser but would recommend finquiz.