Invincible
"my gut is to call her back to the vet"
Then that is your answer. Go with what feels best for you, there is no right and wrong way about this.
Go always with what feels GOOD to you.
In your shoes, I would sit quietly and imagine your cat at the vets office, being happy and well. The less you worry, the better the connection will be. I realise this is not an easy time to let go of the worry, but know that your cat is a vibrational being and will respond to your vibration, and excess worry will block the flow of your message to her.
I would also imagine myself at the vets office with her, and her feeling safe. Perhaps there was a reason why she ran away. If you know why, then I would add that element to the visualisation and make it feel safe for her to return.
I know animals respond mostly to visuals and not words. Once my (silly) dog ran into a field with 3 bulls. He decided to bark at them and they grouped up and started to charge him. I got really worried and was calling and calling him. After 10 minutes, he still wouldn't come out of the field, so I thought to enter the field to retrieve him but as I did so, the bulls turned to face me and were preparing to charge me so I left the field again. But my dog continued to bark at the bulls and get charged at.
Eventually, I just continued to observe but released the excess worry and fear I felt. I went quiet inside myself, shut my eyes and imagined him by my side. 2 minutes later, my dog was licking my hand, by my side. He got the message quickly.
My best to you and your cat
Maya X