First of all you should know what does TMI mean, TMI has other synonyms, like oversharing, or giving out information about excessive personal details. Then there is "information overload," which means entering a cacophony of information. "Too personal" or "too detailed" might suffice on some occasions as synonyms for TMI. TMI is a popular slang word, but these synonyms are variations on the same idea that can work in different situations. Understanding these synonyms will aid an even better expression of the concept within itself, especially in the discussion of boundaries of conversation in both physical and virtual levels.