BPD and bipolar can look alike in symptoms.
The underlying personality organization may be very different.
I have a friend with BPD. I love her dearly. She'd had a severe flare of BPD after some intense life stressors. I had difficulty understanding her words, behaviors, emotions. I really had to study up on BPD to continue to interact in a mutually productive manner.
My point: With my diagnoses, I still could not grasp her experiences, as the inner experiences can be so different.
I don't care for "labels" much. However, they can help us to understand at least some of what may be going on?
Although you may be finding the diagnostic process confusing now, I hope you will find it all somehow helpful in the longer run. My friend and I found it helpful in coming to a deeper, healthier mutual understanding.
Much progress is being made in better understanding BPD. I hold a lot of hope for people living with BPD.

WC