I was once heavily bullied for thinking I had more than one kintype. It made me feel inauthentic. Imm asking you because you seem like a really smart person in this subject, is it possible for someone to have more than one kintype?

Yes, but personally I don’t think anyone has more than like, 8.  Less kintypes are more common and more realistic probability-wise, but looking at it logically, if these things are sourced from mental or spiritual causes, then having a single kintype may not be as common as initially assumed by the community. 

You just have to be honest in your own introspection and meditation and research regarding it.   Ask yourself not what “you like” or “what you want to be” but “what affects you in your actual life”.  Not all the things you have an affinity for are a part of you, but if you feel more than one thing is, then honestly, who’s going to know better than you if that’s true?