Since you are still a minor, your parents have to control you to some extent. In this case, they might be in control of who to enter the delivery room especially if the father of the kid is also a minor or not responsible.
I do believe they are, yes! They are still legally responsible for her and her well being. Unless of course she has been emancipated, at that point she is legally responsible for herself. Fathers have rights too, if your also a minor, you should look into them, see what if any options you have.
I think hospital staff unlimately has a day in how many people are allowed in. If remember right aside from staff they allowed one family member in during delivery and afterwards once in your own room you were allowed more, but as patient i think you have some rights.