Antidepressants can definitely trigger mania. I am not sure that means for sure you are Bipolar I. Have you ever had major manic episodes before or since?

If the concerta makes you calm and more focused as opposed to feeling wired then it is working right. If it makes you very wired than maybe you don't need it for ADHD. It should have the opposite effect from getting wired if it works for ADHD.

I would push against the diagnosis of BP I if you don't have a history other than this one antidepressant. That was a pretty bad episode though.

Even BP II the standard would be a mood stabilizer like Lamictal. I like it very much and think it is safe. I would hesitate on the Lithium.