Why does my homemade pasta sauce consistently have a bitter taste, and how can I balance it out?

I totally get why you're frustrated - a bitter pasta sauce can be really disappointing, especially when you're putting in the effort to make it from scratch. I've been there too, and I've found that the bitterness can often come from the tomatoes themselves, or from overcooking the sauce. Have you tried using San Marzano tomatoes? They're a type of tomato that's naturally sweeter and less acidic, which can help balance out the flavor of your sauce.

Another thing to consider is how you're cooking your sauce. If you're cooking it for too long, the flavors can become concentrated and bitter. I've found that cooking my sauce for a shorter amount of time, and then letting it simmer for a while, can help preserve the natural sweetness of the tomatoes. You might also want to try adding a little bit of acidity, like a squeeze of fresh lemon juice, to balance out the flavor.

I've also noticed that the type of garlic and onion you use can make a big difference. If you're using a really pungent garlic or onion, it can overpower the other flavors in your sauce and make it taste bitter. Try using a milder garlic or onion, or cooking them for a shorter amount of time to see if that makes a difference. And don't be afraid to experiment with different spices and herbs - sometimes a pinch of basil or oregano can make all the difference in balancing out the flavor of your sauce.

Overall, I think the key is to experiment and find the combination of ingredients and techniques that works best for you. Don't be discouraged if it takes a few tries to get it right - with a little patience and practice, you can create a delicious and balanced pasta sauce that you'll love. Good luck, and I hope you find the perfect recipe soon!