Has anything altered since then?- Yes!
is altered the right word? yes it means change, but altered seems to fit elsewhere.
constant self-development ,on the one hand, and passion for art, on the other,
why why the two hand exposition?
prematurely
prematurely as in before other people? before you could control it? explain.
by any characteristics.
what do you mean here?
sufficiently explicit
and here?
this sentence was quite long.
To become an accomplished expert and find my niche and to exert my talents and gifts.
this is still somewhat vague. while you have the commitment to do something, what is this "something"?
Since then my long-term goals have specified: now I see myself involved in the mass media industry which, as I see it, gives golden opportunities for realization of both my creativity and business skills that have developed during the past years and , what is more, for expansion of my relevant experience in mass media.
another run on. make sure those commas go right after the word, like this. don't leave them hanging. what did you mean by long-term goal? the one you mentioned in the previous paragraph? you keep moving onto new little topics, from your self development to your passion for art to your self worth to wanting to be an expert. then this paragraph keeps moving...onto creativity, business skills, experiences in mass media...
You don't outline strongly what YOUR dreams are, nor do you say what your ambitions for the future are...until the end of the third paragraph. make sure tense is consistent throughout. so you want to immerse yourself in knowledge and in different cultures, say that earlier?
with assist of
with the assistance*
your point is made further into the essay, so that part is good. you still need to work on phrasing here and there, but word choice is good, though sometimes misused. good luck!