Hi, sabran. I'm so sorry you're going through this.
I don't know about the others, but with Priscilla, the nosebleeds just got very frequent and very severe. One day we were going to take her for a walk and the nosebleed started before she got all the way down the drive. That was very close to the end. The sneezing/bleeding episodes became much more frequent as well.
It's a hard decision to make and it's hard to tell for sure when it's 'that' time. If the Deramaxx is helping and her good times outweigh the bad, maybe it's not time yet.
Good luck, sabran. Hugs to your girl and for yourself. You'll be in my thoughts and prayers and we're here if you need to talk.