Hi!
If your pregnancy tests are all negative, you are probably not pregnant.
Light periods can be due to stress. Unfortunately, a whopper period often follows a series of light ones, so you may be in for a "storm". If your periods continue to be unusual for you, you might want to check in with your doctor and see if there are any hormonal problems, or other issues.
Good luck!
Dr B
Odds are that you are not pregnant. They say even the dollar store tests are 99% accurate.