Hi UM,
I'm not a psychiatrist/psychologist/counsellor, but it sounds to me as if you have BPD. Mainly because that's my dx, along with major depressive disorder, and you sound similar to me...
I do have a history of volatile relationships, but on the other hand I'm not (I think!) manipulative, so I don't fit all of the DSM criteria either, as this is another of the "core" features. However, as Zloppy says, you don't have to fit all of them to "qualify"

As to treatment... I've read good reports of DBT, but like you I'm in the UK and it doesn't seem to be available where I live. I've been on venlafaxine; actually I've been on a lot of different antidepressants at one time or another - I keep breaking through on them. I'm currently on duloxetine & indeed have been for a couple of years now & it's still working, which is probably a record for me! It doesn't really help with the BPD side of things but does help with the associated depression. I'm also on Sodium Valporate as a mood stabiliser - now that has really helped me! I still get the mood swings but they aren't nearly as violent: in fact I've not felt the need to self harm for months. And I think I've curbed my overspending, though not my binge eating or my smoking, a bit.
I'm now in group therapy. It's going quite well, but it's early days yet and I've not raised a lot of my issues in the group.
I'm here if you want to talk; PM if you like.
In the meantime take care & stay safe.