I'd agree with you where a cat is studying. It's a heartbreaking decision, but one that were can make in love.
BUT
This kitty apparently seems more comfortable now, and doesn't seem in distress. Obviously there's going to be an adjustment period where she learns to adapt to bring blind,
If she's not suffering (which she doesn't seem to be), then there's no quality of life issue. Cats adapt to blindness amazingly well, and my blind cat has a lovely life.
The OP isn't saying about her cat being distressed (even if she was, a period of trying to adjust would be fair), but it's complaining about the impact of having to make sure she's around to give injections, and the cost - a risk which she cost when she actively decided not to ensure her cat.
It's not fair that the cat die because the OP decided not to ensure because she is wary of insurance. The concequences of accepting that risk should be on her, not her cat. Many people who don't insure, open a savings account, which they pay into monthly instead, do they have a pot of money for when their pet becomes ill. This OP doesn't seem to have considered it at all.