Hi AlexOwen,
Sorry to read of your news.
I wonder, are you in the UK? I ask because the blood test results are in an odd form.
I think your AFR equates to the European and UK. eGFR, this is often approximated to % remaining kidney function. This website may help you sort out blood tests, if you are not in the UK or Europe, then search for local information but do take care to verify who is publishing it.
http://www.edren.org/pages/edreninfo/bl ... isease.php If also go to the home page of that site you will find a lot of other useful information.
As rheaybou has already suggested, the best plan is to ask your GP, he knows your medical history.
In general terms, it is important to keep your blood pressure down, (eliminate any added salt and take some exercise) and eat healthily (in the UK the government talks of five portions of fruit or vegetables per day, fruit juice does not count), if this will mean big changes to your diet/lifestyle, it is best to talk it over with your doctor.
Assuming this is not the result of some short-term condition affecting your kidneys, which may be correctable, that is all that needs to be done. If the changes are part of long term kidney failure, it is a waiting game, and no-one knows how long before you reach the point where further intervention is required.
If I have interpreted your results correctly, I would be surprised if you notice any symptoms at the moment.
Best wishes.