I am so sorry; I too have been there very recently, and we lost our girl in September from heart failure. Daisy did VERY well on the meds for almost a full year after diagnosis. We were lucky . . .
I have heard enalipril can have some effects; Daisy was not on this, but on Benazepril, which I think is very similar and is well tolerated. Maybe want to ask the vet. Do you give the Pimobendan on an empty stomach? this is ideal, then I would give her other meds with food.
I know how it feels. My life stopped completely except for her . . I never left her alone, didn't go anywhere, she slept with me and was with me all the time. I have video of her 4 days before we euthanized her, chasing a ball in the park and spinning in circles . . . it was a long road, and there were a few bumps. There will be times you have to adjust the meds, it's a fine balancing act.
I too prayed she would die chasing her ball, or a squirrel
but we had to let her go, and the downward slide happened very quickly. You cannot prepare yourself for this, every dog is different. All you can do is love them and try not to mourn your beloved yet. There will be loads of time afterwards to cry