lain

I understand you, bro.
I've also "adopted" the personality of anime girls before. I've switched who was I was LARPing as many times before, but settled in a particular one.
Instead of what people are saying here to you, I think this means quite the opposite of having no personality.
Having a "guiding character" makes you understand yourself better, to know what kind of person you truly are. Most people lack this basic kind of self reflection, because they're boring pieces of shit who can't see their lifes carved into a character's.
What I'm trying to say is, you're not really "adopting" a new personality. You just related to a character because of traits you already have.