My mom has trouble with her words all the time, and I notice it's because she's trying to use overly complicated words. I think she's trying to come across as knowing more vocabulary than she does.
I understand what you are saying, but in my case that's not what I mean when I say I can't find that "just right" word. It's not big flowery words, but just normal words that I lose. For example, yesterday I was talking to someone about a civic club fundraiser and I couldn't find the word "chairperson." Ordinary, every day word, but it wouldn't come. After stuttering for a moment, I had to say "the person in charge." Not a big deal when it's just an occasional thing, but when it happens every day, it's very disconcerting.