When I lost my cat, did she know I loved her?

Two days ago, I lost my sweet childhood cat of 16 years. That morning before work, at around 5am, I saw her on the sofa laid out and I pet her. She made a low grumbling sound, like she was in pain, but she may have been purring too, I can’t remember. I came home from work and she was in the corner of the living room, breathing hard and making the low grumbling sound more. I called my sister and we got her to the vet. She cried when I picked her up, and she cried in the car a bit. They took her and came back an hour or so later, saying she was in critical condition and her liver was failing, or she had stomach cancer, it was hard to say. But her vitals were too overwhelmed and she had fluid in her stomach. Considering her age and her condition we decided it was best to put her to sleep. When the vet brought her in she was crying. She calmed down and laid down when we sat together. I cried my eyes out and told her I loved her, kissed her forehead, petted her, but she didn’t really respond beyond those low grumbling sounds, but I did pet her through the whole process. It was so hard, but I couldn’t let my best friend die alone. Since then, I’ve been a mess. She was in my life for 16 years, I don’t know life without her. She loved my family but she was closest to me. She would sleep with me, come to me for food and to have a nap on, she’d play with me in the morning in my bed. She would cry outside the shower and get upset if I was gone for too long. I guess I’m only struggling to process her death. She must have been in so much pain, and it will haunt me forever that I didn’t get her to the vet that morning. I really didn’t know she was sick, I thought she was only tired. She was 16 but still so active, and healthy looking, I didn’t really question it. Did I do everything right? The only thing that matters to me is, does she know I loved her so much, and tried to protect her and comfort her? I hope she felt me there it’s killing me to not know