How do I provide clear and compelling evidence to be considered as de facto custodian?

I live in Kentucky and have been taking care of my grandchild full-time for the last six months, including providing all food, clothing, toys, etc., taking her to all her medical appointments; taking her to visit with the mother's family; etc. I want to file for custody, but the statute says I will have to provide "clear and compelling evidence" that I have been caring for her. I've not kept receipts of my purchases (I really thought this was a temporary situation at first and I love my granddaughter and am happy to do anything I can for her), and I'm not sure what other evidence to which the statute might be referring. Would statements from witnesses (family members, friends, doctor) count as evidence? What else might I use? Thanks for any help!