I am 17 and diagnosed with emotion regulation disorder. Because I turn 18 in 2 weeks I am now having conversations and questionnaires for a more specific diagnosis in cluster B. I will know in a few weeks if I get one. If this is not my place, please delete my post. Possible TW for self hate and harm.

So like stated before I have emotional dysregulation, since I was 12. I have had therapy but I dont feel like it ever worked. Over the years it has gotten worse.
I cant handle someone canceling plans with me- especially people that are important for me. My boyfriend just cancelled plans with me for the millionth time and I am freaking out again. Every time he does this I have a breakdown. I instantly think he doesnt love me anymore or that other people are more important than me. I dont really know how to put it into words. 
When I feel like this I want to hurt myself again or simply die. Even though I am years clean from cutting. Or I start calling him 10 times in a row. Start spamming him. Saying he doesnt love me if he doesnt come over RN. He already broke up with me twice.
I ruin it everytime and after it I have so much regret!! And hate myself even more. Does anyone have tips?
I will have therapy again after my diagnosis so I have nowhere to ask rn!! 😭😭😭