First and foremost..you are NOT looney!!! I'm lucky enough that I work afternoons so I get most of the day with my 14 month old. I feel ok about working knowing that all I miss is her supper, bath and bed. Although I do miss bathtime.
I take care of my niece while her mom and dad are working during the day. I know it's hard for my sister-in-law so what I try to do is email her pictures of her daughter at the park or playing with my daughter..or even sleeping. I think it helps her to know that her daughter is ok. Her favorite part of the day though I think is coming home from work and seeing her daughters eyes light up when she sees her and she'll run up and hug and kiss her mommy. It lets her know that while she well taken care of while mommy's at work..mommy is the favorite
Hope that helps a little.