Remove the hanging shelves.
Hang shirts, jackets and pants hung over a pants hanger on the existing rod. Place boots/shoes on the closet floor, shoes on first step, bins for socks and underwear on the second step, and folded jeans/tee shirts/sweaters on the fourth/fifth/sixth steps. Hopefully then, everything fits in the closet, with enough room to shift everything to the left a bit when the attic needs to be accessed. If more space is needed, single stackable shelves could be added to the steps, with out-of-season clothing toward the top/back. They will probably need to be removed to pull down the attic door.

I have seen people turn the steps into drawers using the space within the stairs- an idea anyway. Otherwise, just use use containers the length of the step (so it is easier go move when required) and within the larger container, use smaller ones to organize if need be.