Okay, I'm not always the best about communicating via interwebz so I'm going to try to not sound like a snarkass.
Because this is a general thread and I'm not on here everyday, I don't know the story of how you found her or the details of why you decided her vs other dogs you were looking at.. I know you said the meet and greet went really well and that she was a shelter pull. If I remember correctly, you were looking at: Pei and mixes (sorry I don't remember so well). Maybe a BC was on your list? I know you said that you didn't normally care for a herder mix and frankly they are a world away from a Pei.
So, I'm going to ask the question. *puts on flame suit* How much research did you do on ACD's? Because frankly, everything you've listed is EXTREMELY normal and probably why she ended up in the shelter to begin with. They are controlling, loud (yeah... Cattle Dog shriek is a thing), they herd and bite things, and the girls are bitches. Especially when they come from a shelter situation into a strange environment and don't know how to manage themselves they revert to instincts. Which is to herd. And sometimes to YELL AT ALL THE THINGS. And push people and dogs around so that they feel a sense of control. She needs you to give her a sense of purpose. Teach her to relax. Teach her to behave in a crate. Tether her to force her to settle. Teach her tricks and stimulate her mentally. ACD's thrive off order and work. Workworkworkworkworkaholics.
I think you either love them or you hate them, and I really hope you learn to love her. In order to this you HAVE to give her a chance. It's only day two and you aren't giving her a chance. All you are doing is wishing you had kept looking. You aren't doing yourself or her any good by doing that. You need to spend time with her WITHOUT Astro around, and you need to make sure that you and Astro have alone time together as well. You also need to do things with both of them.
You will either get into a groove of two dogs and love them both, or you won't. I challenge you to give her two months, at least. If by two months you still really don't feel like you jive, then make the decision. Because nobody wants to live with the dog they hate and frankly it isn't fair to either of you.
Oh, and do me a favor. Check this out:
http://chazhound.com/forums/showthread.php?t=171193 There is a lot of good advice from fellow Chazzers on here. I've been here and we got through it and Rider is a completely different animal because I gave him the benefit of the doubt. Sometimes you don't get the dog you want, but you get the dog you need. That is what a fellow dog friend told me going through his rough patch and I can't tell you how true that holds. I think you will find that this little ACDx will change your world, and hopefully for the better.
Also, aucado.us is a great ACD forum that I recommend you check out. I know this came out long and I'm sorry, but I hope you are able to take something from this post to help you.