I read Flowers in the Attic at that preteenish age, and now that you mention the title I'm sure I also read My Sweet Audrina and maybe lined it better, but I can't bring to mind any memories of it. (As opposed to FitA, of which I remember a couple of key scenes and the general plot.)

I also read a lot of Lois Duncan, probably before the VC Andrews, which come to think of it is...less transgressive (and actually aimed at preteens or teens, which I don't think VC Andrews was meant to be) but kind of in the same lineage?