Fitting: not enough drop (maybe)

[rhodesengr]

So I have a Benelli Supernova 28" Realtree Max5.  I understand it isn't really optimized for Trap but I am using it mostly for trap. Being relatively new to shotguns, I am trying to bone up on proper fitting. It feels like it doesn't have enough drop. If the stock is on my shoulder, I can't get my cheek down on the comb without getting my head tilted. If I bring the comb up to my cheek with my head/neck in a natural comfortable place, the butt pad is well above my shoulder. The SN came stock with the "B" drop shim in. I put in the "C" shim in and increased the drop 5mm. I have the "D" parts on order but I am wondering why it seems to far off. If the D shim isn't sufficient then what can i do?

I think the LOP is also a little long but I am not sure if I shorten the LOP is that will make the drop issue better or worse. It is not exactly easy to adjust the LOP. The stock butt pad is 1". There is a .5" pad but no one has any and pretty expensive. I have a slip-on .5" pad on order to give reduced LOP a try.

I have no idea what size person the SN was designed for but my size is pretty average being 5'9"