Not having high blood pressure is a positive and so is not being diabetic. I am diabetic and so I am at risk of kidney problems so try and do as much as possible to maintain my circulatory system. A family history of circulatory disease is also a risk factor on top of this.
Doing everything you can for your circulatory system. Things like Serrapeptase and Nattokinase might help restore the circulation but may take some time. Eating Natto a japanese food can supply large amounts of nattokinase and vitamin K which would be helpful as vitamin k helps direct calcium to the bones rather than the circulatory system. Vitamin C helps stabilize the circulatory system and provides an essential nutrient for the circulatory system.
The state of your nervous system in the kidney could be a factor as it affects healing and can cause autoimmunity towards the kidney which could cause damage.
With kidney disease you do need to be careful not to overload the kidneys which would be under functioning. Supplementation needs to be balanced to prevent overload.
Take a look at Pauling therapy because it can be helpful for circulatory problems which might be beneficial. This includes fairly high dose vitamin c and other nutrients which you might need to use reasonable amounts rather than the maximum to limit any overload.
Look at anthocyanidins/proanthocyanidins which are colourings found in many fruits and veg particularly berries such as cherries, blackburries, grapes, blueberries etc. Grape seed extract is quite high in such things but would be without the high carbs found in many berries which would be unhelpful. Limiting carbohydrates would be helpful to avoid sharp rises in blood sugar. This can cause an elevation in cortisol BTW.
Limit your omega 6 fats as these can be damaging. Take Omega 3 raise your intake of this helpful fat. The omega 6:omega 3 ratio is usually far out of balance. Ideally it should be closer to 1:1 but is often around 15:1. Polyunsaturated oils are to blame for this.
I do all of this myself.
Take a look at iridology as it might reveal reasons for your problems. Any obvious markings in the kidney zones will be the nervous system rather than showing kidney disease but could affect healing and potential autoimmunity. This often shows as a grey marking. Kidney disease shows nearer to the outer rim as a white or yellow marking in the circulatory zone and extends inwards the worse it gets. Grey markings which is a reduction in the iris fibres affects healing and immune system control which would reduce healing. This is extremely common in many people and does not mean kidney disease itself but could affect healing and maintenance which could make it more likely. I have seen people who develop acute kidney failure with these markings following infections because the immune system control is poor. One such person did recover from the infection and did regain working kidney function but not 100%.
It would be worth investigating homocysteine levels and trying to keep this low. You might have problems with folate metabolism which can increase homocysteine which can cause high levels. Some people have problems with folic acid a synthetic form of folate which means that their bodies cannot convert it to usable forms. It can also affect natural folate usage in the body which can cause functional deficiencies. Natural folates are preferred or supplementing with usable folates rather than folic acid.