If I were you I would stick with it for now (if part of your feelings are based on the three sessions so far) and see how it goes. You can always pull her out in a few weeks if you feel like it. I personally think childcare offers good structure and different opportunities. As PP have said, I think I'm a better mother now because of it. I always think my son is happier and has learnt things he might not have just with me. I also end up more able to spend quality time with him because I do jobs/errands/work when I can while he is in care, which leaves me open to just being with him after I collect him. I remember you were frustrated by the sickness aspect, too, and as frustrating as it can be I'm hoping that will pass soon enough.
Other things I would think about - are you likely to look for other work soon? Is it a childcare that may be difficult to enrol in again at a later date ie is there a risk of it booking out? If that happens, what is the possible impact for your family?