I know what this is all about cause I’m on accutane for the third freakin time in my life. It helps me for a few years then I need to take it again. If you’re really fed up go to the doc tell him your are tired of this and want accutane. Soap wise - if you can find the acne prone bar by neutrogena - it is by far the best soap out there. Second place is Dove.
As far as pinning down what is the cause it sounds like it is just genetic since it never completely goes away - I’m the same way.
Good Luck.