The problem with bladder stones is that the frequency of the bleeding and the amount of pain that she is in from the bladder stone will increase until she'll be in total agony. As the stone grows, it will make any operation even more difficult and will lower the odds of her making it even further. It will also damage the bladder tissue and that can bring its own problems.
My Minx lived for more than one year after her first op, but the damage from the first stone had not only caused constant and severe cystitis, but at the second op the vet found a (most probably cancerous) polyp with only a small, flat stone as a consequence of the constant irritation. It wasn't the second op that was the reason why Minx had PTS about two weeks after her second op, but the fact that we could NOT get on top of the inflammation in the bladder caused by the all crystals and stones.
Can you get painkiller from your vet to be able to keep her comfortable while you make up your mind? You still have time to think hard about it.
I am so sorry to be the bearer of such bad news! After all the heartbreak I went through with Minx I would so wish for nobody else to have to go through that.
Another big aspect is that neither the op nor the treatments she will probably need for the rest of her life will be cheap. I spent several hundred pounds on Minx. Can you afford that and how far are you prepared to take things?
I include a pic of Minx' first bladder stone. The colour is from the blood during the op. If it's too gory, don't look at it!