When cards are not coming

I have been playing sngs the whole year (my first at poker), beginnning with the (painful) $1.50 + 0.25, and going up to the $6, which I have been playing right now. My current ROI for these $6 is over 50% so I probably shouldn't be complaining, as it used to be 5% for the $1.75 and about 12% for the $3.40.

Everything should be good, but recently I noticed one disturbing thing in my style: I'm never the big stack or the chip leader. I'm almost always in the money, but I'm never the guy terrorizing the whole table, and getting a big enough stack to put pressure on the opponents. This only happens when I have a good run of cards right in the beginning of the SNG, otherwise I'll be stuck to the middle/low stack and having to wait forever for some opportunity to double up.

The question is: what should I do to not to be so card-dependent player? In the $6 tourneys, unlike the $1.75 and $3.40, players are tighter so it is possible, to some extent, to play in a more aggressive way, but I can only play this style when I'm getting cards.

Oddly enough, when I'm sitting there with no cards, and I manage to double up once or twice, and get a reasonable stack, I can put pressure on everybody with a *very* aggressive style, and if that happens when we're down to the last 5, I'm usually going in the money fairly easily.

Summarizing: I'm sick of being of the low/mid stacks. Please help me become one of the big stacks

Information taken from pokertips.org