I'm Bipolar. Why am I stuck on a hamster wheel?

I'm a junior in high school. I'm going insane. My mood changes many many times during the day. I cant stop repeating songs and phrases and sounds in my head. I imagine extravigant conversations with real people, but inside my head. I've told my mom and she brushed all of it off as teenager stuff ( I just turned 17 a little over 2 months ago). When i'm in a hyper state I am so loud and tell jokes and am impulsive and dont stop smiling. When I'm sad I just keep smiling and tell everybody I am justtired. When I try to be serious with people they think i'm joking. I have too much more to say. But the last thing is...whats so wrong with me that included in all this I dont feel safe or comfortable and im paranoid but when i wasin the hospital I felt so safe and comfortable and actually liked it. That was last school year. I got put in bcause my parents found out I was taking pills that were lying around the house and common stuff like that.