We found our daughter in very much the same way as you. We met our birthmother in Feb and she was due in June. Our daughter was born in May because E ask to be induced. We became very close to E during those three months but she was young and there were times when she would say she was going to call and didn't or when she would take days to return a phone call. There was even one time when her phone was disconnected and we had to drive to her apartment, 45 mins away, to contact her. Needless to say, we got her a phone after that!
I think I would leave her a very nice, none pushy message until she returns the call.