It sounds like you are taking excellent care of your wound, and that is to be commended. There are many things that can keep even the best treated wound from healing, however, and we will discuss some of the more common ones briefly. The key in your specific case is that you will need to see your primary care doctor
to receive the appropriate treatment, although you don't mention how long you have been caring for this specific wound.
Things that delay wound healing include external factors such as increased bacteria (it sounds like your routine care would be sufficient to prevent this), internal factors that affect the response of the cells that do the work of healing, such as tobacco or diabetes, both of which are notorious for delaying the healing process, and architectural issues that have to do with the way that blood supply comes and goes to the wound. Obviously, too little blood flow getting to the wound, such as would be caused by vascular insufficiency if you have smoked throughout your life or have atherosclerosis for other causes, would cause delayed healing, as would too much blood, which could be caused by chronic venous insufficiency. Your doctor will be able to guide you in which one of these, or another problem, is affecting your healing, and you should speak with him or her soon.