I've been seeing my T since November of 2015. I feel safe in her office and tell her most everything. I started seeing a psychiatrist in February, and he diagnosed me with depression and generalized anxiety and gave me scrips for both.
Now my T has never said to me what she thinks I may have (possibly because she's a doctoral student so maybe she feels unqualified) but I know from my psychiatrist (who has access to my T's notes) that my T thinks I have bipolar.

My psychiatrist, who I have only ever had two appointments with, says he thinks the bipolar diagnosis is "soft." I know he has a medical degree while my T is still working on her PhD. But wouldn't my T know more than him? She really knows me, she really listens to me. The only questions my psychiatrist has ever asked me about how I feel are if I feel suicidal and how I'm feeling in that moment.