@Sirine ,
Arghhh. such a common thing...that is, mistaking BPD for bipolar.
Symptoms can be quite similar, but treatment is so different.
From experience, it seems the BPD episodes cycle very rapidly. Moods can switch by the moment. e.g. if something bad happens, then the borderline's world is turned upside down. Conversely, if something 'good' happens, then the person with BPD is on top of the world.
BPD treatment requires longterm psychotherapy.
Bipolar is less reliant on the current environment and therapy involves medication in most cases.
I'm not a specialist. I'm only speaking from experience.
I'm sorry you have to have this confusion...i don't know what else to say...
Hugs, tyme