guilt and anxiety about returning to work

Is anyone else struggling with the thought of going back to work? I have to return full time, 40 hours a week. My in-laws will be babysitting so I'm not worried about her safety or anything but I just feel terrible about going back. I'm scared that I will miss a lot of "firsts". I'm scared that she will forget me. I'm scared that she will bond better with her caretakers. I know I can't be so selfish like this but it's hard not to be. Can anyone give me advice or encouragement? I'm sure I'm not alone with these thoughts. A few hours during the week and the weekends just don't seem like enough time to be with her.