Do you have a contract? I think your first problem is your working too long. You need to shorten your day. I run from 6:45 - 4:45 ... I used to close at 5:30 and that was way to late for my family. Tell the family they must feed their child before arriving as breakfast is not provided and the next meal time is not till xxx oclock. Stay firm with that. Have you and your daughter chose some special toys that she doesn't have to share and keep them in her room or up where the daycare kids can't get at them and bring them out after hours and on weekends. The toys I have in my daycare are not my children's toys they are mine and that way there are no sharing issues.
Maybe if you make a few small changes like closing earlier, having a contract and stop letting parents take advantage it might make you feel better about things. Then you will geable to make the decision if it's still what you want to do. If you do decide to close you should give the parents at least 6 weeks notice.