MotherFaith directing you to that article in Wikipedia is a good move. I've read it several times as it helps me understand the why's of why are we attracted to diapers. Linked to the article is Love Mapping and you should read that as well.
I think you're sort of in a middle position where your mother isn't totally against it nor is she accepting. My mom, when she found out, sent me to see a psychiatrist at a residential mental facility. Your mom may decide to read the Wiki article or she may not, but if she does, she should realize that infantalism is not related to pedophilia other than they both fall under the broad umbrella of Paraphillias. Give her some time to accept all of this as the passage of time diminishes the shock value.