Exactly. Printing trillions of dollars is the most certain way to hyper inflation.
Why hasn't it happened? The Fed has started printing money to buy T-Bills (quantitative easing) but the CPI and PPI are both down (deflation).
The only answer I have is that credit is being eliminated and debt paid off (deleveraging) at such a rate that as the money supply has increased the available credit has decreased. I think we may see stagflation even with all the paper that has been printed. I don't believe lending is going to increase dramatically because credit worthy borrowers are preparing for a long downturn, the baby boomers are retiring (looking to downsize) and the "echo boom" is half the size. Also factor in the increasing govt spending and tighter control of private business and you don't see a big boom ahead.
Without the expansion all the money being printed is just sitting there, it's not flowing through the economy.