The conclusion I wrote for my MSc was pretty much what you say above. But then we're in somewhat different fields, and maybe the expectations are different.

Research-wise, my project was a disaster, but I got a good degree on the strength of the approach and quality of the write-up. Essentially, I referred back to the Aims chapter, and stated how I'd attempted to achieve each aim, speculated about why it hadn't worked, and suggested how one could approach the problem in a why that might give a meaningful result.

I don't know if that helps, but there you go :)