Wow I think that therapist needs to chill out, just because you have bi-polar does not mean every personal choice you make as to what to do with your physical appearance has to do with it. I have had short hair, and I do kind of like it some people close to me like it when I have it long but its not their hair which they respect at least.

I have long hair now since its been a while, but I will probably try some shorter styles again. I think it seems like people in your life need to have more respect for you and your personal choices...rather than assume any change is due to 'omg bi-polar'.