It depends why you did a horrible job at testifying (and you may have been better than you think). If you think you did a horrible job because of pain, pain medications or mental issues you're fine. I always tell people that if they're having a terrible day, the judge can see what a terrible day is like. If you're having a good day, you can tell the judge about your bad days. Also, some judges are friendlier than others. Just because a judge is short with you or you don't think was listening, it doesn't actually mean anything. The judges tend to rely on the medical records quite a bit anyway. If your testimony really did hurt your case that the medical records would otherwise support, you can appeal your case.