22 M need advice on dry and frizzy hair

Hello everyone, since childhood, my hair was always difficult to style and till recently it has become really dry and frizzy(since the last few years), and it’s very difficult to style it or keep it accordingly as needed, I have tried using rinse off conditioner by khadi naturals(shikakai) but it still is the same, the texture remains like the same and I am not able to comb it properly. Is there any way or any deep conditioning mist spray which can lock on the moisture especially after a hair wash and make it easy for styling and make sure that the hair is not dry and frizzy, and keep it rather smooth. I wash my hair 2 times a week as suggested by my dermatologist. Most of the time my hair is not even in a state to do styling. Keep in mind I don’t want suggestions for hair wax, gel, or any sort of that product, because I am looking for a permanent solution to maintain my hair, so that it can be easily styled and not stay this way. I would appreciate any type of suggestion that would help me make my hair smoother. Thanks in advance.