which has persisted for last six years is most likely androgenic alopecia
. During this problem, the hair root progressively gets damaged by a process called miniaturisation. At the final stage the hair root gets so weak that it can only give a thin hair called velus hair. It is unlikely to improve with medication now.
If you are keen to get hair in the bald area, you should plan a hair transplant
. This is a surgical procedure by which healthy hair roots from the back of your head are transferred to bald areas. You should meet a good hair transplant surgeon in your area to know whether you are a good candidate for transplant or not.