My Dog Has Kidney Failure She Is 15 Years Old

My dog has kidney failure she is 15 years old our vet said because of her heart condition and numbers climbing rapid he feels we need to make a very hard decision for her she has almost all of the 10list she isn't hardly eating hardly drinking water and for two days she has not gone number two everything is happening so fast all she does is sleep and has started shaking once in a while I feel her quality of life has changed so much she is a wonderful dog it is so hard to make this final decision for her once in while she will drink or eat but not to much lately what would you suggest we love our Vet and truly trust him