text: Getting on the pill is the best way to ensure a regular period. It is also great for helping with premenstal discomforts. Irregular periods are much more common than you probably think. So many things can affect it, such as: stress, excessive exercise, change in eating or sleeping habits. Talk to your gyno. One more thing, being that your pretty young, your county health department most likely offers free birth control based on your income. Check it out you have nothing to lose!