frizzy hair help

Ok so I've got this thing going on with my hair for almost all my life now. I can't control the frizz. I have a lot of hair but it's also thin, it's naturally volumous and wavy. When I'm at the hairdressers they tell me it's new baby hair (not damaged or anything) and that it's just a matter of waiting until the hairs are grown but I guess my head just makes new hairs on a daily basis haha. Since I have this as long as I remember I've tried a lot of things including products aimed at treating frizzy hair. Different shampoos, conditioners, masks and more natural solutions like henna/cassia and natural oils. This is what my hair routine looks like now: I wash my hair about once every four days. I wash it with a natural soap bar and use amla mix as conditioner. When I started this routine it really seemed to be helping but somehow it's just back to normal now. I let it air dry (blow drying makes it worse) and apply jojoba oil on the lengths. What helps the most is style it with like curling iron or something but it only helps when I stay inside, and as said I have thin hair so I want to keep away from too much heat treatments. Dying/treating it with henna or cassia made it also better but I don't want red hair or copper glow anymore. I feel I'm kind of out of options but since there is so much out there I'm sure there are things I haven't tried so I would love to hear from the frizzy haired girls here how they keep the frizz to a minimum :) This is how my hair looks like now, I washed and treated it like described this morning.