I have not ever shared this story here on Chi People because I'm not proud of it, but I really feel for you so I am going to talk about it.
I've been in your exact situation before. When I moved from my home in the US to Sweden, I immediately tried to "replace" the family Chi I grew up with at home with an 8 week old puppy. After 5 days, I was hysterical in tears every day, waking up in severe panic attacks, feeling unbearable anxiety, and regretting my decision because I wasn't ready for a brand new Chi puppy yet. I hadn't researched, I was completely unprepared, and I had not found this forum. I was also still missing my old Chi and all the stress of the new puppy was making it even harder on me thinking about how much I just wanted my old Chi back. My boyfriend was really worried for my emotional state, so we agreed upon reselling her to a very nice family in our town that actually wanted her from the breeder she came from, but we were the first to go see her so that's why we got her. After we sold her to them, I felt even worse because then I missed her as well. Several months later, I got Gemma when I knew I was truly ready to tackle having a new puppy. I had none of the regret or anxiety I felt with that first puppy, but up until I got Gemma, I felt so awful and regretful for rehoming that puppy before her. I was missing both her and my old Chi every day until the day we brought Gemma home.
If I were you, I would not rehome this puppy. I guarantee you are going to feel even more regret. I know it's so difficult to fight the stress and anxiety, but believe me, there will be more if you rehome her. Don't make the mistake I did. Don't try to "replace" your old Chi, Chanel, like I tried to do. This puppy is going to be completely different and you are going to grow to love her for who she is individually. Gemma is nothing like my old Chi and she is nothing like the puppy we had for a few days, but I love her more than anything.
If you ever need to talk or would like advice or help with anything, my inbox is open here. Hang in there. It will get better. Trust me.