I have had 2 bitches spayed, one at 10 and a half due to pyometra and my current girl.
Back in the 80's, my breed, Belgian Tervueren, were very susceptible to anaesthetic and so there was absolutely no question of her being spayed!! When she contracted pyo, i was terrified but anaesthetics had advanced by then and didn't have so much effect on the liver, but were passed out more quickly. She came through very well for an older dog.
My current girl, well, i dreaded thethought of an op. in case it went wrong, much like you. With my first Terv i had had to go for it; this was a choice. In the end it came down to the fact that the breed needs such a huge amount of exercise, and mental stimulation, that it was impossible to keep her happy at home and in the garden. ( I had managed before but i had also had my male BSD who was had been neutered because he was a unilateral cryptorchid. I think he kept some other dogs away and we walked very early. He also kept her busy.)We were both climbing the walls. I took her out to a part of the New Forest i rarely saw people, and dammit if i didn't meet an Irish setter all on his own - well, he had brought his brother along!! So i was desperately trying to call his owner, who was it turned out half a mile away; keep my own dog under control (she was very good) and fend off these two excited male dogs with one thing on their mind. It was dreadful. I found myself wonderig what Irish Setter x Belgians would look like!!

Anyway that did it for me, with my particular breed and in my circumstances i felt i had to have her spayed. It was horrible taking her in, and in fact i rang up about 10 minutes after i got home - to STOP the op - and they had already done her and she was recovering nicely!!!
I was so relieved.... i hate messing with animals and it has to be down to your choice in the end, but unless you have a good set up at home like many breeders do, or a private area to exercise, it may be very difficult. If your dog can cope without a good walk for a few weeks, you may be able to manage :)
Lindsay