Here's what I would recommend:
(1)breaking up your chords...using arpeggios of the chords instead of playing the straight chord.
(2)Also your "touch" is important too......the dynamics of how soft/hard you press the keys.
Very rarely will you play all the notes of the chord at the SAME time at the SAME volume/velocity...thats just banging out chords, and it sounds like thats what you are describing as your current playing. Even if you are playing the right chords, no matter how "phat" and full they are, played like that would sound very, as you put it, "amatuerish".
Those are the two things that i've focused on in the last few years, and i've seen a night & day difference in my sound!