Anet A8 bad/inconsistent extrusion after changing nozzle
To be sure it's from your nozzle / extrusion mecanism, you could check calibration by extruding (in the air) 100mm of filament, and check how much it really uses. If it uses 100mm (or so), then the problem comes from any other parts (bed, filament feeding...).

If this is really an extrusion problem, first you can check again your extrusion step motor gear. If it's ok, then you could put back your old nozzle to ensure the new one is the problem... If all is ok with the old one, then yous should have something in your new one, or it's not a .4mm ?