Question about euthanasia

This past Friday we had to put our family dog down at age 14.5. It was incredibly peaceful, but still so heartbreaking. I’m glad she had the beautiful ending surrounded by love that she deserved, but this all brought back the excruciating pain I experienced 6 years ago. I had to put my beloved dog down after a battle with an autoimmune disease that showed up out of nowhere and in the end she had a blockage in her stomach and the emergency vet hospital that we’d been working with during that time told me the humane thing to do would be to euthanize, which I was devastated by. The thing is, her euthanasia wasn’t as peaceful as our dog this past week which has taken me back to the day I lost her and has me questioning if the vet didn’t give her the sedative first and I’ve been spiraling ever since Friday thinking she had a traumatic death (it certainly was for me). When she got the injection she went from sleeping to jumping up as if someone was at the door, and then she immediately laid back down and she was gone. Did the vet not give her a sedative? Why did her last moment make her jump as if she’d heard something? I struggled for an entire year with woulda, coulda, and shoulda beens, questioning whether id done enough, whether the emergency vet hospital advised me right, and thinking that’s just what happens when i dog gets put down. I warned my son not to watch on Friday but other ppl that were there had never seen their late pets have anything but a peaceful ending. Can anyone weigh in on this? I’m torturing myself with the memories and worrying that my dog soul mate had a terrible ending.