Indecisiveness-not my best quailty

So, I am a little nervous and uneasy and I don't really know why. I am very indecisive when it comes to myself and personal decisions but I have decided to take some Mondays off while I can. How this came up was originally when I interviewed for my job I asked about working a four day week still since it would still be considered full time and I would still have benefits. My boss entertained the idea but then decided that she needed someone at my school full time. I agreed to it because with all the breaks you have off and the hours I figured it was still worth it to take the job.
So with me just starting the job and the first of the school year my case load is still kinda low so I emailed my supervisor and asked about 4 days a week again if the case load remained low. I didn't really expect a definite answer. I expected maybe a "we'll see how it goes".  However, she met me half way and said that I can take Mondays off  (because there will be another therapist there on Mondays) until I reach my case load number that it needs to be but that she still needed me there full time. I am totally okay with this and think that things will pick up.They already kind of have but for some reason I feel weird about it. I feel like I should still be at school if everyone else is there. I feel weird about Nash not going to Mother's Day Out on Mondays. I feel like I am doing something wrong and don't really understand why.
 I hate that about myself. I am trying to just be excited about having an extra day with Nash  and enjoy things this fall with him like going to the Zoo, The Pumpkin Patch, the park, etc. I know I won't ever regret getting to spend more time with him while I can. I know this won't be permanent and if I wanted to I could still work Mondays or every other Monday or something. So, I am puzzled about why I feel weird about it. Maybe it's because it still is a relatively new job to me and I don't quite feel at ease with it yet. Maybe it's because I feel like people will think I am not committed to the job if I am already being off more than I originally agreed to. Maybe it is because I really do like the job and have gotten attached to my kids and the staff and I feel bad not being there every day like they are. Maybe it's because it is not really permanet so it will be changing and I don't really like change and some times can be way too rigid. I like predictablity and stability. Maybe it's a little bit of all those things.
(Okay, there you go. A glimpse into my crazy, over thinking  things mind. Not pretty my friend)