Extremely painful periods; help?

I need advice. I'm going to tell you about my periods. I am not one to play the victim card, but I legitimately feel like I lost many days of my life to my debilitating period pain, that I strongly feel is more than just dysmenorrhea and I feel the need medical advice to learn what was/is going on. Here we go.

I got my first period when I was 12. Every single month, for the first 2 days of my period (lasting on average around 6 days) I would be in absolutely debilitating pain. I would say I have a relatively normal pain tolerance, and I can say without a doubt the pain I experienced from my periods was worse than anything I've experienced. It would start with lower back pain and painful cramps and escalate into extreme fatigue, dizziness and excessive sweating that lasted about 30 minutes. It was always too painful to stand up and I would be curled up in fetal position after taking several Advils, waiting for the pain to go away. I had to leave school each time to go home because of this. Sometimes my vision would go blurry and I would not be able to see my hand if I put it in front of my face. I would feel like I had to pass out for 10 minutes. Every time this would escalate in nausea and ultimately throwing up. I would never feel better until I'd throw up at least 5-10 times. This happened each month from the time I was 12 until I was 18, when I finally decided enough was enough.

After doing a decent amount of research, I decided to take control of the situation and go on birth control (age 18). After being on the pill for a couple of months, I noticed that my periods were much lighter and I no longer had the dizziness/ nausea/ throwing up. I was on the pill for about 3 years, and I've currently been off of it for about 6 months. I no longer have the same issues that I was experiencing before I went on the pill.

Some other information that may be relevant: I'm a 5'7" 130 pound female. I'm currently 22, I exercise regularly and have a relatively healthy diet. I am on no medications, and the only medication I've ever been on was the birth control for the issues described above. I have been diagnosed with major depressive disorder, and my mental health is something that I have struggled with in the past but currently is very well under control. I have no other diagnosed medical conditions.

I would really, really appreciate it if anyone is able to offer any insight as to what was going on with me. I strongly believe that suffering from these severe issues was not simply just "period cramps" or me "overreacting." I have a degree in biology, and I am very interested in this topic, so please do not spare me the details.

1) What are possible diagnoses for what I've described?

2) Why did the severe pain/dizziness/ throwing up stop after I came off of the pill? Can I expect these issues to resurface after a certain amount of time, or is it not something to worry about anymore?

Thank you so much! I apologize if this post was too long, but it was something I had to get off my chest in full detail!