Hello, I'm Dr. Deb and will do my best to help you today.
I'm so sorry that Jessie has been diagnosed with a heart condition and that your financial situation is what it is.
While I don't like to second guess fellow professionals, I should mention that it's very difficult to diagnose congestive heart failure based on an x-ray alone. Typically we would need an ultrasound to adequately evaluate the heart and to make this determination.
But, regardless, the drugs which are commonly prescribed for this problem can affect the kidney which is why blood work is usually done prior to starting medication....something which I assume your vet told you.
Unfortunately, the medications we use are prescription only so if your vet is insisting on bloodwork first, then this may not be something you may be able to do much about.
However, I can suggest an over the counter cough suppressant such as Dextromethrophan which may help with her coughing. This is a drug that I'll often use in my patients with heart issues and who are taking cardiac drugs. There should be no harm, in other words, for her to take this drug even if she does have congestive heart failure....or even if she doesn't.
The dose would be 0.25 to 1 mg/lb 2-3 times a day. You just want to double check labels and ensure that the formulations only contain this ingredient although inclusion of Guaifensin is fine.
If Jessie isn't coughing as much, then it may help to improve her quality of life which, after all, is what's important.
I hope this helps. Deb