Hi,
Yes, it's possible that your last (16 day) period moved up the date that your next period is due ~ it could have changed your cycle up a bit. If you're concerned about pregnancy, take a pregnancy test. Depending on your age, periods can become irregular (shortened or lengthy, even skipped); for example if you're in your 40's you might be experiencing perimenopause. If you're in your teens periods can also be unpredictable sometimes. It's wise to keep in touch with your doctor and keep tracking your cycle. Good Luck