Pinkmada,
These other folks are right -- you need to be referred to a urologist. Ask your GP to refer you and take copies of your test results.
If your GP thinks you were misdiagnosed, then why aren't they looking into it further to find out what the real diagnosis is? I hear your frustration loud and clear -- and the very BEST thing you are doing is listening to your own intuition in pursuing an answer.
I was misdiagnosed, too. I was told I had cancer and I would be dead within 6 months if I didn't begin chemo! I trusted my intuition and figured out on my own that I didn't have cancer. I got my test results, and looked up all the words I didn't understand, and eventually proved that I had been misdiagnosed. It happens everyday and people get sicker because they don't advocate for themselves.
So keep trusting your intuition -- and stay on top of your GP until s/he sends you to a urologist to review all your tests and symptoms.
Good luck to you.