Yes, I agree. If you can't say it, write it.
Besides it sounds as if you're an introspective person to begin with, maybe writing it out would be better. And then, you could always print it out, then read / say it to her, looking at the bullet points for a quick reminder on what you wanted to say next. Or if that is too difficult for you.
Then you could just write her a letter and leave it for her. Start it out by saying something like. "I'm sorry that I wasn't able to bring up these things to you in person, but these are ongoing issues that have been weighing on me for some time. We've been together so long, I know you understand how difficult it is for me to deal with in person confrontation, so I really, really appreciate your understanding that I've put these things down on paper.
"These items are important to me, and I'm not sure how to bring them up to you. Could we talk about the things I've written below tonight when I get home?.... etc."
I don't know, I kind of think that if you write her a letter, that it will get some of the mis-communication that's been going on, out of the way, it might reduce some of the anxiety you're likely feeling around her preparing meals. But if you write, you should soften the intro, so that it's not a huge whammy out of no where. She likely thinks things are fine and has no clue that you're really upset over these things.