It does sound like BP (not BPD, I'd say).

At any rate, it usually takes a long time to be properly diagnosed, but they may prescribe meds before that time. I was diagnosed after 7 years, but I've been on antipsychotics after the first few weeks, the third visit or so. It took so long to diagnose me because the dosage was very low for acute mania and it didn't work very well. It clearly wasn't enough. They didn't know much about BP because I would only admit having some problems with anxiety. The psychiatric nurse recognised it as psychosis but the psychiatrist specialised in anxiety disorders. It was also difficult to diagnose because it could just have been one episode of mania/psychosis and not a (more) chronic condition.

I've also been diagnosed with BPD.

After a second long period of mania followed by (with some overlap) non-affective, incongruently fearful psychosis they finally diagnosed me. Another thing that made it difficult is that I'm quite chronically affected, so to speak, having schizoaffective disorder, bipolar type. It's more of a developmental disorder than BP is (generally; it's a quite heterogeneous group).

Maybe you can ask for a second opinion if you believe it's really a problem or could become a problem. I would then suggest you ask for a mood stabiliser (which can be an atypical antipsychotic), not an antidepressant.