Feel your pain, I've had acne since I was 15/16 - the cystic kind too which is even worse. The only thing that's really worked for me is a combination of omega 3 tablets (I take flaxseed oil ones because I'm a veggie too) and cutting out sugar from my diet. No white bread or pasta, no flavoured yoghurt, no fruit juice, the whole shebang. It sounds extreme but it's made such a difference to my skin.
I've tried antibiotics, but they came with really unpleasant side effects, and benzol peroxide - which does work, but isn't something I fancy using long term.