Just a couple points before you sell your frame for a bigger one...

I would just drop the saddle first without changing anything else and see how that feels. That should remove some pressure on the lower back immediately. If you feel the need to drop the front end -

You said you had 10mm of spacer under the arm pads which you could remove.

It also looks like to have a top cap / spacer under the stem - remove this, the Aduro bar does not require a top cap. That will give you a few mm more drop (and remove those visually annoying gaps between the stem and top tube and between the beard and brake covers! In fact do this anyway...).