find the money to board her at the vet. That way they can keep an eye on her, and you will have peace of mind.
Our cat got very sick this past fall, and he ended up needing surgery -- the week before our wedding and honeymoon. He basically needed 24/7 care anyway, so we boarded him at the vet, medical boarding (which is different than regular boarding). He was scared and unhappy, but i felt a lot better knowing that they would be watching him for any signs of trouble, all the time. I actually was glad we were going on vacation, because if we weren't we wouldn't have really had a reason to board him, and i would have been sick worrying that we were missing a sign of relapse at home. The vet will ask you about the level of care you want given to her before they have to call you, you can specify a dollar amount or you can say, do everything up to surgery, or everything up to cpr, or whatever. Our cat is also only three, and we had pet insurance (didn't cover the boarding but luckily covered a lot of his medical care), so we told our vet to do whatever they needed to do to save him (if necessary) while we were away, since we would be in a foreign country and difficult to reach. Everything worked out fine, and they didn't need to do anything medical to him while we were away, but i felt soooo much better knowing that he was under their care.
If money is truly a huge issue, talk to your vet about it. They want to help our pets as much as we do, and they will usually try to work something out with you, like a payment plan, if necessary. There is also care credit, which can be extremely helpful in these types of situations. Good luck to you and your kitty. I know exactly how you feel and how difficult this is.