I often feel embarrassed about the mistakes that I make on a regular basis when speaking my own language. To this day, I, a native Greek person, can't conjugate the verb 'παράγω' (produce) properly. While it certainly is easy to speak fluently and write fast with correct spelling (well, most of the times), eventually there comes a time that I have to use trickier words and I'm usually left stuttering in search of the proper word or conjugation in a web of loosely connected syllables, where I should walk carefully on the correct spider thread, lest I find myself falling down the pit of shame for stepping on the snapping thread of a wrong answer.

A dramatic description, I know. (and it probably has some grammatical mistakes or whatnot, but I think I got my point across).

Is anyone else having this problem? Do you think that the reason behind this may be education? 

Also, what do you think about having native teachers who are not qualified for teaching (have not studied in any university) yet speak their language perfectly? Is it better to have an uncertified native teacher, or to have someone who has received education for teaching the language without being a native speaker?