I have extreme and unstable emotions. What is wrong with me?

Hello doctor,

I am a 23 year old female, 5 feet and 8 inches, 285 lbs; currently taking Seroquel 100 mg at night and Adderall 30 mg on days I have to work. I have a history of depression, anxiety, self-harm, drug abuse, obsessive thoughts, and chronic fatigue. I have gained 40 lb weight in the past six months. Previously, I was diagnosed with borderline personality, and have been on two psych holds within the last five years, completed two three-day stays for in-patient treatment, most recently four months ago. I was told I might be bi-polar. I cannot motivate myself to get out of bed unless I have to go to work. I have a history of toxic relationships and abandonment issues. I cannot seem to stop thinking about what happened with my most recent relationship even though I know he was not a good person and did many bad things to me. I have overwhelming feelings and feel things in extremes. I have a history of drug abuse, mostly Klonopin, Xanax, and pain medication. I am clean since four months. I have a history of reckless behavior. Now that I am not abusing pills, all I do is sleep and eat and compulsively spend money. I feel lost like I do not fit anywhere. I am upset about my weight gain, but cannot motivate myself to do anything about it. I want to go back to school but cannot bring myself to do the work. I was seeing a psychiatrist five years back for similar issues from another relationship and was diagnosed with borderline personality and was put on multiple medications that did not help me. So, I stopped going and stopped taking the meds and felt better. I got myself together and went to school and graduated with honors with associates in radiologic technology. I was alright for those three years and it has been pretty downhill the past year since I met someone else and it went horribly wrong and affected my job, which I quit due to my ex being there, which then cost me the job I was just offered because my previous boss gave me a bad reference. I lost the opportunity at a great job, and since then it has been very hard. I got reckless. I was taking way too many pills. My relationship with my mother was strained, and it got out of control. I cut my wrists with the idea that I did not care what happened, and that day I was admitted for an inpatient treatment for three days. I have not abused anything since then, but I am miserable. I just want to know what is wrong and why I feel things in such extremes.