This is how I would nerf Poppy.

Remove the damage from her ult, make the ms scale with level, and either reduce the max health damage on her W to 6/12 from 7/14 or make it scale with level (3/6, 4/8, 5/10, 6/12, and 7/14%).

And now a chunk of damage is gone from her kit. Maybe, I do suck at math and am possibly missing some factors.