Hey dugout, welcome to the Tech Forums. Glad to see you here.
In answer, when you say you are measuring BH to the back of the string do you mean to the side facing you or the riser? It should be the side closest to the riser. In any case, as much as it may bother you, I'm not sure I'd mess with it a whole lot if it's shooting well. Bow specs are usually a close approximation of where a bow performs it's best, but can be jiggled to suit your own needs. String and cables can be twisted around and played with to get the bow just right, but it often just isn't worth the time and effort. And you may not care for the feel of the bow afterward.
I know mybows are hardly ever "in spec". I adjust draw length, draw stop, cam orientation and such to what feels best for me. I really tweak them and sometimes for months. I just keep trying stuff to see if I can make the bow fit and feel better for me. Once I find that I measure the specs of the bow and record the data into my user manual and they are what they are. Only reason I record them is (habit) so I have base numbers to work with in the event I change the rigging----or continue the quest for the perfect feel.
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin/Rytera Staff Shooter
PSAA Life member, UBP Life member
PADI AOW Diver