Emax Veneers - Shade Issue - Would whitening the backs of my teeth help with darker color? (Photos)

I've had laminate veneers done twice, shade BL3. I had them re-done as they weren't fitted properly, but now the shade is darker, despite the dentist saying they have been fitted in the same way with the same shade BL3. I think it's due to 1 the translucency of the veneer / cement used and/or 2 my natural tooth colour darkening over time, therefore now showing through more. Can anyone offer any advice please? Would whitening the BACKS of my real teeth help at all?