I recived terrible word from my cat's vet that she has two growths.?

The growths (or tumors) cannot recall exactly what she said, one is near her kidney and the other is in her ovary and that likely they are cancerous. Vet recommended I think of euthanisia as my cat's quality of life is very poor and soon to get worse. This confirmed fears I have had since poor NeNa began vomitting a few mo's ago and ultimately stopped eating 10 days ago. She has absolutely no appetite whatsoever. I am heartbroken as you can imagine. My NeNa has been with me for 12 yrs and 3 mo's and I am devastated beyond belief. My question is when a sonogram is performed is the digestive tract taken into account? Someone mentioned she could have an obstruction in her digestive tract by perhaps haven eaten something out of the oridinary. Though my cat is not a very playful cat so I really don't see that having happened. I guess I will call the vet tomorrow and ask them this question as I forgot to ask today. I just could not leave her there today to get put to sleep. It pains me greatly, beyond belief to even fathom doing so. This is really difficult. I wish there were more I could do but vet said that no amount of money is going to restore her quality of life. I do not want her suffering and I have to come to terms with this. But I can't help but wonder if there is something more I can do. The vet gave her a shot for nausea, pepticide I believe she said it's called. I asked that they give her some IV fluids. I am so lost. When she got back today, she's leaving track marks of poop and smelliness. This had never happened before. Could the tumors/growths really be causing her to vomit excessively and lose her appetite completely or could there be more to this? I really need some closure. I don't want to feel like there was no rock left unturned, though I know myself, and am and will be questioning if everything I did was right and enough for her well-being. Perhaps, I am simply not doing enough!