hey, I posted here before but I need some further advice

I’m almost 18 (turning 18 in may) and have been experiencing a lot of symptoms of BPD (not knowing who I am, having unstable relationships around me, a lot of self destructive behaviors, uncontrollable anger, my mood can change in an instant and is usually intense, a crippling fear of abandonment and have had my fair share of dissociating)

I have brought this up in the past and my therapist only brought up BPD once and hasn’t mentioned it at all. I mention it to my dad and he thinks I’m trying to fit in with the cool kids (by having a personality disorder? I don’t think so lmao) 

I just really need some guidance, how can I show people that what I’m experiencing is valid and that there is a possibility I might be suffering from this?