If the shelter was giving up.. she could probably sense that they didn’t care to try anymore… cats can sense things. After six month, she’d probably given up on anyone ever loving or wanting her again. Keep at it, she needs to know that you won’t give up on her. She wants to feel wanted and loved. Right now, she’s scared. That’s understandable. This is a new place. You are unfamiliar to her. Give her time. Don’t get frustrated and yell or get loud. That’s the worst thing you can do. She needs to see you both as good hoomans.