First off, congratulations Caitlin. You're a senior, that's awesome, keep up the good work.
Now that you're a senior, we can now tell you the secret. Time goes forward. Second by second, minute by minute, day by day, it goes forward at the speed of life.
But you asked where it went? If we remember Einstein's theory correctly, if you can travel the speed of light, time would essentially stop. But, presumably, you're not traveling the speed of light. So time, for us, simply goes by. Somewhere into the fabric of the universe. The actions we take simply vanish into the cosmos. Much like the actions of all those who have gone before us.
If it's not too late, we recommend a philosophy course during your senior year so you can learn about this and other important life questions.