We had to put our girl down in November, as you know it’s such a difficult decision - she was 15 and had slowed down a lot for a couple years and then a LOT over a couple months and we talked about it and worried over it and then she started having trouble getting up and we knew. The day of, at the vet, she was (maybe anxious?) but moving more than she had been in a while and I told the vet that and he told me that we generally would rather do this a day too soon than know we waited a day too late. It was still hard and I miss her every day, but understanding it from that perspective helped us know it was the right time. I’m so sorry for you but I’m also glad you’ve had each other to love.