I have a tip for getting a sweeter sauce without sugar. Use carrot in the sauce instead of sugar. I know it sounds crazy, but you should try it. I would recommend taking 1/3 of your sauce, and cook it with a decent amount of coarsely chopped, or even whole carrots. Cook it low and slow for about an hour, or until the carrots are soft. Then remove the carrots, and mix the cooked sauce with the rest of your uncooked sauce. Then you have the best of both worlds. The fresh uncooked sauce flavor, and a natural sugar provided by the carrots. Again, you do not leave the carrots in the sauce. Somehow it makes your sauce sweet without a carrot flavor.
Also, I totally agree with the Stanislaus/Escalon recommendation. I have tried at least 30 kinds of tomatoes, including San Marzano's, and nothing beats them. Their sauce comes nice and thick, so you don't have to cook it down like you would with the brands you find in the grocery store. If you have to buy store brands, stick with the Huntz and Pastene.
Grande is creamy, melts great, and doesn't easily burn, but the flavor is just not that great. Can you find whole milk mozzarella from Sorrento, or Great Lakes? One of my favorites was Axlerod, but it has been discontinued. The parent company also sells Maggio, and I think it might be the same thing as the old Axlerod. Great lakes has the best flavor of all, but it is a little more oily than Grande. It almost like it has butter in it. Also, there is a new style of mozzarella that is becoming available around the country, and most of it tastes better than Grande to me and my tasting crew. The foodservice industry calls it cryo-pak. It is a pre salted fresh mozzarella packed in a vacuum sealed plastic. Bel Gioioso, is the best, but Grande, Poly-O, and others are showing up in grocery stores around my area. Sometimes it is called fresh mozzarella, sometimes Fior Di Latte. You know when you see it because it is pure white like fresh mozzarella (the kind in water), and the plastic around it is a tight form fitting type without a lip,or rim. I think someone on this forum has actually found the Poly-O cryo pak at sams club for $2.50 a pound.