It's possible to have both, as many people with ADD have grown up to develop BPD as well. Not because they've had a traumatic childhood, but where their needs weren't met as they were younger with this difficulty, they are likely to develop BPD.

Don't forget, a lot of people with ADD alone have issues with anger/depression etc. as Didgee mentioned.

People with ADD always score high on those kind of internet quizzes. Don't pay attention to these please, and you definitely don't want to be diagnosed with BPD.
If you are doing fine on your medication, then stick with that.