T.W.
I don't think you can give him too much attention, especially at 12 months. I certainly wouldn't feel guilty about that!! My first child would go to anyone without fussing while my second is very attached to me and cries a lot when I first leave. They're just different and both so normal. I think if you try always leaving him with the same sitter, he'll begin to get used to her and figure out that you're coming back. One thing to try would be to invite the sitter over to spend time with both you and the baby, that way she can spend time playing with the baby while you're still in sight. I think it will help with the adjustment of you actually being gone for a few hours. Over time, it will just get easier for your baby.