How can I make my senior lutino comfortable?

[Luffbox]

I've had my baby girl for roughly 7 years. She is an estimated twenty years old. I rescued her from a negligent owner that caused her permanent liver damage, arthritis and partial blindness. I've done all I can for her health wise, but she has gotten to the point that anymore car rides are out of the question. Our last ride together was only fifteen minutes and it caused her way too much stress. I don't need medical advice, I need to know how to make her as comfortable as possible. I know she is tired and it's frustrating. I won't take her in to be put down because 1) I'm selfish because I don't want her to die, and 2) I'm worried that her mate would follow her over the rainbow bridge if I did so. 3) I feel she would rather be at home when the time comes. My question is, how do I make her comfortable? Am I a bad birdy momma for not putting her to sleep? I need help. This has been bothering me for quite some time.