I too have a 3 year old, and we've been in the habit since he was 1 of me just feeding him lots of possible sentences to say to express what he might be wanting

I too have a 3 year old, and we've been in the habit since he was 1 of me just feeding him lots of possible sentences to say to express what he might be wanting to say. If I get it close, he repeats verbatim. If it's not what he wants, he rejects it or twists it to closer to what he wants. And yeah, probably a decent portion of infant emotion is on not being able to communicate. Those who learn infant sign language have a better time. Being able to sign "I want the water, not more food" versus being unable to communicate is a massive difference. Adults get used to this sort of feeling of incompetence if they embrace always learning new skills. They can even get skilled at accepting it without frustration. But tons of adults avoid these things and basically stop learning entirely new skills and don't understand the value of accepting child-like novice learning. I, for one, get pretty antsy doing anything I'm good at already. I'm only ever interested in stuff where I feel there's some challenge to work on and something new to learn.