How to overcome erratic mood swings in a teenager?

Hi doctor,

I am a 14-year-old (turning 15 in six months) girl who is 5.1 feet tall and weigh 101 pounds. Ever since my early childhood, I have been experiencing rapid, intense mood swings that last from a couple of days to two weeks. During these days I am "high," people have noticed that I tend to talk too fast and too much. I sleep less (four to five hours), come up with too many ideas at once, and start too many projects that I do not complete. They have also noticed that I tend to think less about the consequences of my reckless decisions and pursue fun most of the time. This "high" usually lasts from a few days to a week, and my "low" period usually lasts for two weeks. I alternate between them usually, but there are also times that I feel fine before my low period starts up after a high one. The onset of both is sudden without any reason. However, during the days that I am "low," I have noticed that I cry for no apparent reason, most of the day because of guilt, feelings of worthlessness, and suicidal thoughts. I also prefer not to interact with others and keep to myself, even with my closed ones. Although it is during days like these that I tend to get a lot of sleep, I still feel fatigued nonetheless. My parents have noticed these erratic mood changes, and I was previously diagnosed with anger management issues when I was very young. However, they have not taken me to a psychiatrist and refuse to take me for the diagnosis and treatment of my behavior. They believe that I can handle it on my own and would instead not take any medication. Recently, however, the mood swings have been much more difficult for me to handle. As I type this, I believe I have been in a low mood for precisely a week now, and the suicidal thoughts and feelings of worthlessness have worsened. Kindly help me.