What I've learned is, if you're worried you're faking it or don't have it, 9/10 times you've got that specific diagnosis. If you're really sure you have BPD, you should talk to your therapist/doctor, address your symptoms.

I'm in the same boat, I've tried to tell my partner that I think I have QBPD but he basically just told me not to worry or think about a diagnosis because then I can just place all the blame on my mental health and not take any responsibility for my actions and behaviour. I just think that it will help me to better understand WHY I feel the way I do and how I can be patient and gentle with myself. But I keep second guessing myself... I often think maybe I'm just making it all up in my head and it's not as bad as I think it is. Feel free to pm me if you want to talk :)

Absolutely pursue a diagnosis! You might ask a mental health provider to test you for a personality disorder instead of specifically BPD to prevent confirmation bias.

If you are dealing with the symptoms of BPD, you deserve to get help/treatment for them. Definitely look into getting officially diagnosed if it would help ease your mind, but I think it's important to note that the diagnoses in the DSM describe surface phenomena while ignoring the underlying causes, and many of the diagnostic labels lack scientific validity. It's sometimes more helpful to pursue treatment for the symptoms you know you have rather than getting caught up in what diagnostic label best describes them