Don't play it so softly. Seriously, if you were to play this in a hall and you played the notes so soft that sometimes they don't sound, then people in the back won't be able to hear you at all even if they do sound. Remember that the RH is just playing the accompaniment, so focus more on the LH instead. If, in order to get a good balance between hands, you have to play the RH almost inaudibly soft, then you probably aren't voicing the melody enough. Concentrate on the melody and it will be easier.