What stipulations can I put in like seeing her on the weekends, on her birthday and Christmas etc.?

If there is no judge order for grandmother to have legal guardianship, go say hi to grandma, thank her for watching and tell her you ahve it from here. She may try to go get a guardianship when you do, but she has no legal superiority to a natural aprent without a court sanctioned guardianship You might give the police a head's up as you head that way, and you can not wreck the house, but the child is your child, not the grandmother's ward, unless and until ac ourt says otherwise.