My son called me MIMI and my mom MOMA
when he was about 3 1/2 it finally came thru as Mommy and Grandma, he just couldn't pronounce it.
We always call aunts and uncles ''aunt Deb", why not grandma Cathy.
Some fall back to their nationality, nona, gemma,tia, ect. how about that why not grammy or grannie(that sounds like you need a rocking chair). Let us know what you pick.