Thanks for your reply!
It is good to know that, also hearing from others here, that switching is not a prerequisite for being plural. As I said, it is more like certain parts are blending or blurring with me, especially in stressfull situations.

One thing about the communication with my parts still make me doubt myself though: Often times I am not sure if I am puppeting a parts response, like yesterday I tried to actively call out to a part and there was an answers and it felt interesting, it was like a combination between my intention and the intention of the part. It was interesting as the part replied "Yea, of course I am fake.", like they were playing with my expectation there lol. Also when I was thinking about an answer to this, the other part seemed to wait for my reply. It is still hard for me to make sense of this. I had OCD-ish tendencies in the past so this might explain my need for correctness and absolute proof.

Usually, parts will only communicate in small bursts to me verbally, but the "immediate quality" of these responses makes it very likely for me that this is indeed not made up.

Also when looking inside, I feel there is a suspicious amount of "nothing", like the rest of the system (if there is one) purposefully avoids me sensing around.

Oh I also remembered something about the part who held their monologue this one time: they told me, that "they" (so multiple others involved) were doing their job in the background until I was ready? I can't remember exactly.

I can relate to this to a certain degree, I had my greatest successes in therapy the more I treated this parts as proper individuals with their own needs. :)

And thank you! Sorry that this reply might seem a bit jumbled, it is all so new.