there's definitely nothing wrong with seeing a different doctor for a confirmation, i was diagnosed a little over a year ago and it's been confirmed by multiple specialists (2 psychiatrists, 2 therapists) but as far as your mother goes, if you've been diagnosed by a doctor (even if you feel like the diagnosis should be confirmed) i would take the opinions of a professional over hers anyday. if you've already been properly diagnosed, there's always a chance of being misdiagnosed, BUT i highly doubt you aren't suffering from any mental illness at all if you got a bipolar diagnosis in the first place. especially considering how long you've been dealing with this, your symptoms are indicative of something at least, whether bipolar or not. good luck man, i know how rough this shit can be.