What do you mean by "discoloration"? I see a large area in your picture that looks a little darker. Is that it?

I used Gloss White too, but my paint looks very uniform. Could the discoloration be your primer showing through? I do have a few areas where my primer went on rough that show through the main coat. That's the only discoloration I have, but it's not that bad and I doubt anyone else would ever notice it.

Also, the scratches, are they from buffing or are these scratches ones that are underneath your paint that didn't really fill in? If they're scratches from buffing, are you using the white Turtle Wax Polishing compound? Because the red Buffing compound can cause very noticeable scratches because it's so coarse. It can also leave a very bad red discoloration, especially on a white paint job.

Using the very limited info I have to go on at present, it sounds to me as if you might need a few more coats, and / or to thicken up your paint a bit. But that's only a semi-educated guess.

Also, did you give the paint several weeks to dry completely? The color variation could be areas where the paint has not completely dried and hardened yet.