Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

You are right to talk to a psychiatrist about this; that is the first and best step to take to sort all this out.
Welcome back!
I hope you get healthy again soon. Good to hear you've had a run of good health last couple years. All the best.
Obviously a professional needs to answer your question, but if you're just have the extreme lows without the highs, I would at least question the bipolar idea. It's certainly worth discussing with a trained therapist.