What you describe could very well be what they call a mixed state or mixed features (or episode). If it's episodic (it's not something you've experienced all your life, more or less) and you respond well to antipsychotics, I think it's unlikely it's ASD.

Do you generally have some kind of paranoia (i.e. did you notice you had been after taking antipsychotics)?

Have you ever had strong paranoia without (severe) mood fluctuations?

Autism originally was a set of symptoms that was considered part of schizophrenia.

Do you have difficulties socialising and, if so, why?

I don't believe you can have both (and I dare say a growing number of people don't).

ASD is most probably overdiagnosed because it's common practice to rule it out before looking at other possible disorders and because there's more stigma attached to the more severe psychoses, like schizophrenia. Schizophrenia and BP aren't considered developmental disorders, while ASD is. Developmental disorder are generally ruled out first (this diagnostic hierarchy is part of the DSM, but the DSM is only a guide, not something to solely base a decision on).

Edit:
Problems sleeping (at times or somewhat) can be sign of both ASD and BP.

If you're often unsure about what people mean or expect because you can't tell, it's likely ASD. If it's because you're very wrong sometimes when you feel you absolutely know what people mean or expect, but you can't reasonably know that and you haven't based it on anything you've read or analysed, something (maybe mildly but chronically) psychotic is probably the problem.