That's rough. I'm sorry your fish is sick.
This is a tough decision for anybody to make. Some people will say "
euthanize the fish," others will say "give it more of a chance to heal," and still others will say "nobody can make that decision for you." I'm in the last camp.
I will tell you this: No creature enjoys being invalid like this, so she is suffering to some extent.
I also know that swim bladder problems are difficult to heal.
That you're asking this may mean that you realize that she's suffering but are loathe to take another creature's life without being sure you're choosing the right path. I'm like that. When any of my pets have been at the point that quality of life is a concern, I've opted to wait far to long to euthanize them. It's easy to see in hindsight, but really difficult to accept while you're looking directly at it.