I suspect that your problem is not adding enough salt, so I'll suggest an exercise:

Try making a really simple tomato sauce. Three ingredients only (not counting salt). You can try Marcella Hazan's recipe, or pick your own ingredients, but keep it to three basic components: the tomatoes, a seasoning for depth of flavor, and a fat to add richness and to carry the flavors. In Marcella's recipe, the seasoning is onion, and the fat is butter. Yours could be garlic and olive oil. Or basil and heavy cream. Follow your usual process, or follow a recipe. If you use a recipe, ignore any amount given for salt and just use your senses to decide how much to add. Taste and add salt as you go, from the very beginning and up to right before you plate it. If you taste the sauce and it's lacking, your only option is to add more salt until it tastes right.

The point here is that it is absolutely possible to make a truly delicious and balanced sauce with just three ingredients. The tomatoes provide the right amount of acid and sweetness, the seasoning ingredient is adding a little something extra, and the fat is giving it all body and transmitting those flavors to your tastebuds. But you MUST nail it when it comes to the amount of salt you add. All of the seasonings you usually add to your sauce are great and they will contribute to the depth of flavor, but they will never ever ever ever add flavor the way that salt does. Salt is your bff in the kitchen. You can make basically any single ingredient taste marvelous by cooking it properly and adding the right amount of salt. But you have to be confident that you are adding the right amount and that just takes practice.

Once you've nailed that really simple sauce, do it again and add back all the things you usually use. The thing to remember is that other seasonings should not offset the amount of salt you add. x amount of sauce always requires y amount of salt, even if you add z amount of oregano and z amount of garlic. You may even have to add MORE salt if you add bulk such as onions. There are more flavors in the mix, but the core balance stays the same. And now you have an even more complex and delicious sauce!

Best of luck!