Some basics on passata:
You shouldn't need sugar, the onions have sugar and the sweetness should come from the bay leaves.
It's better to cook the bay leaves in the oil, and its better to cook the pepper in the oil (unless you buy powder pepper)

Don't add salt until it's on the table. Why? Well sometimes you will want to cook something salty in the sauce, today I cooked bacon. Bacon adds both the fat to cook the onions and the salt and richness, any cured meat will be much the same.

Instead of anchovies I added fish sauce, I don't like anchovies but the sauce still needed the pungency.

I 3/4 cooked the pasta then added it to the sauce, both thickening the sauce and flavouring the pasta.
You can also cover it in tinfoil and bake it as if it were lasagna, if you're keeping an entre warm in the oven this helps time other dishes.