Can I take my child

My ex girlfriend is keeping my 7 month old daughter from me.
I was kicked out of the hous in mid July. We have a 7 month old together and I have been raising her 6 and 4 year old as my own for the last 2 years. They call me Daddy and I have supported them financially, neither one of their fathers are involved. Until 2 weeks ago I was able to go over see the kids, take them overnite, phone calls and I have been giving my ex money when I get paid.
She has now moved, changed her number, ignores messages sent on FB ( I have no other way to get in touch ) and has stated if I show up at the new place she will have my ■■■ beat. I just want to see my daughter. There is drug use in the house and my ex lives with another woman, between them there is 9 kids in the house. My ex does not work.
I am going to file a custody complaint but have read that could take time. I want to see my daughter now, it’s already been 2 weeks. If before then I am able to see my daughter do I have to give her back? With no custody agreement we both have equal rights correct? Can I be forced to return her? I can provide a stable, loving environment. And as much as I want the other kids I have no legal right to them.

That is correct that without a custody order or other custody agreement, you would not have to return your daughter to the mother.

You are also correct that a filing a custody action against the mother takes some time - there is not an immediate court order or court date and you must complete custody mediation typically before a court date. However, if you believe your daughter is in substantial risk of bodily injury or sexual abuse, you may be able to ask the Court for an ex parte custody order, which is an emergency temporary custody order.