I read that\ struggling to think of word to complete sentence is sign of dementia. but i'm only 32 and dealt with this since jr high. dementia?

Don't be silly: It's only dementia if you could do it before and have now lost the ability. And isolated dysnomia is not dementia. Demented people lose a lot, and it gets relentlessly worse. If you were born with a little glitch in your brain that causes difficulty with word retrieval and nothing else, that's not dementia by any stretch.

Probably not: Some struggling for word finding is perfectly normal. If you are really concerned, see your doctor about a mental status exam or a neurology referral. It may reassure you that everything is fine and also give you a baseline from which to evaluate any future potential losses.

?dyslexia: You are young for true dementia, and I suspect your issue involves a congenital learning disorder. Many psychologists could either directly help or refer you to a specialist who could address this.