Having had some time to think this one through a couple more things, he's probably used to a lot of different (mainly) women turning up at various times of the day with; food, cups of tea, medication or whatever so don't dress like the staff, if they all wear blue or white go in red or yellow, dress like you don't belong in the home, like you're from the outside world.
In his head you probably are still there but it may be as a 12 year old, consider in that time how much you have changed, I'm not suggesting you go in a school uniform with pigtails but he may remember you as what you were like not what you're like now, taller, different hair any number of ways you're not the person he remembers as "little Essie" just out of primary school.
As we say on here "you have to live in their world, because they can't live in ours" and in his world you're still probably a little girl not what you've grown up to be.
K