What people are telling you is that if you hold an irrational belief alone, it is a delusion, but that if millions of people have a shared irrational belief, that that is different.
I would agree. It's not that your beliefs are more irrational than virgin births and resurrections, it's just that you are the source of your belief, and the others learned theirs from a book or from clergy.
Your belief seems harmless to me if you don't act on it, so I disagree with those who recommend professional help unless you begin making decisions that affect your resources or safety based in that belief, although I can't imagine what that would be.
Belief in reincarnation sounds near enough to A Groundhog Day existence metaphysics to me to say that neither makes much more or less sense than the other.