I’ve had the same experience with DuckDuckGo — the results just aren’t as complete as with Google (or Bing, for that matter). I always found myself doing another search using Google just to make sure DuckDuckGo hadn’t missed something.
Whichever browser I’m using, I always turn on the Do Not Track option in the browser preferences. Doing that seems to remove most of the problem with ads following me around the internet.