The #1 culprit for this is a monitor that is set too bright.  Calibration doesn't address that.  The best thing to do is to print a standard test image on standard paper.  I don't see any metallic glossy papers listed in the P900 driver and a lot can happen when using/adding new media types so it is best to start with a standard test on a common paper like standard Epson Glossy.  See if you have the same problem with that.  If so, it's likely your monitor is too bright which is causing you to edit or accept photos too dark (which is how they print).

Regards,
Mike

No, Qimage uses the Epson driver and can't bypass anything in the driver as the driver supplies the requirements and all software has to obey those.  Those (density) settings may not apply or be available if you have color management turned off: if you're using a printer profile in Qimage.

For estimating ink, there may be some third party ink utilities that can estimate ink usage but I believe they estimate how much ink has already been used and they don't "predict".  You'd have to Google that because Qimage doesn't do any ink predicting as it has no access to ink delivery amounts: the driver doesn't supply that in any way.

Regards,
Mike