Letting children come to your home is great. It lets you see exactly what is going on. You don't need to feel that you would be 'stepping on toes' if you have to be the 'mother' in any situation. If your daughter begins acting out of line, it is time for the kids to go home
You might also consider having a get-together with the families. If you have the time or money, maybe you could walk with your daughter to the homes of her friends with plates of cookies just to say 'thanks' to the other parents for allowing their kids to come to your home for play dates.
But, if it gets to be too much or you don't like the behavior that is going on, it is totally fine to tell the kids that it is time for them to leave. They are at your home and need to treat you with respect.
Also, it might be a nice idea to call the parents of the other children to let them know that they are there playing with your daughter. Even though you've said they don't seem to care, you could simply say something like "Hi, is this Joey's mom? This is Sarah's mom. Our kids are in the same class. I just wanted to let you know that your son is here playing with my daughter. Is this alright with you? I know if my child were off playing at someone else's house, I'd appreciate a call too. I just didn't want you to worry and wanted to let you know that your son is just fine. Oh, hey, by the way, we'd love to have your family over for dinner or a play date sometime so we can get to know each other."
Saying something like that can take the pressure off and make the other parents feel more comfortable. And, if you like the family enough, you might be more willing to let your daughter go there for a play date occasionally. But, if this is something you're uncomfortable with, that's fine. She's your daughter. Simply tell the other parents that you are perfectly happy to have their children over to your home but you would prefer that your daughter stayed there and her friends come over until she is older. If they don't like it, that's just too bad, lol.
God bless,
A.