[OMFG!You'reActuallySmart!]

No doctor will diagnose you with bipolar and depression because the disorders are mutually exclusive. Any depression you would experience would have to be from bipolar or another non-mutually exclusive disorder. Sorry, you haven't done research giving you correct information, even Wikipedia will tell you otherwise in less than 10 minutes. Further research would tell you there's different types of bipolar disorder (i.e. reading parts of an online DSM-IV-TR).

Since you say someone's voice makes your emotions change, that suggests you are very sensitive but not bipolar because bipolar is not from someone telling you anything, it's an internally-driven pathology. What you described is external stimuli that affects you because you are very sensitive. That also indicates low self-esteem, low confidence and other things. Not bipolar nor depression. Less than 10 minutes on Wikipedia will tell you this.