I'm there too.
Ive crashed so bad. My psych who diagnosed BPD this past year (i was diagnosed with it also when i was about 20, im 42 now) says now that I am bipolar2, which is his way of explaining my better periods of time when im not depressed and my horrible periods of time like right now.

I also have been previously diagnosed with ADD, as the symptoms are very similar to BPD really- with emotional dysregulation being a big factor in both.
If these things come out of nowhwere and are not in fact a reaction to an real or perceived stimuli, then often a doctor will bring up Bipolar.

I would talk to someone.
You were on lots of meds for someone so young, those meds not normally recommended for anyone under 18, and that alone could have made your life more difficult. (I swear that although Paxil was great for me, the first year I was on Prozac ruined my brain for life, lol)
You could be suffering from depression, and depression does cause us to turn towards substances to numb ourselves, block out, and sooth... then again, so can BPD, and BiPolar and even adult ADD (was reading an article which suggests ADHD -with or without the hyper activity - and BPD may be a subset of the same disorder) --
point is, at some point labels do not matter.
Feeling good does.
Get help with what you are feeling right now, without trying to figure out where this is coming from, to avoid any future harm to yourself.
Just extend some compassion to yourself, and a hug, and see if you can get some assistance from a doctor.
Im doing the same on wednesday - im totally falling apart
(((hugs)))