how to improve the consistency of my pizza sauce
The key to good tomato sauce is the rate at which you heat it. The instinct is to just get it boiling and thicken it up in twenty minutes but this results in horrible tomato paste.

Instead, simmer the sauce very slowly for say four hours and you will get a much better result. You can do a big batch and it will keep very well in the freezer.

The long slow heating will make the tomatoes fall apart, but if it's still too chunky then you can always blend the sauce.