<snip a sad tale of glue slippage>
Do the glue up with say a max of three (3) laminations.
When cured, laminate a max of 3 laminations together which provides a
total of 9 layers.
Use epoxy and let cure at least 48-72 hours in the clamps.
Been there, done that.
BTW, forget sand in the glue, does nothing but make a sandy, weak, joint.