Please Your Question Here Am 26years Old I Use Postnor

Please your question here am 26years old I use postnor 2 after having an unprotected sex but for the past 3 to 4months now I no longer have a normal mestra cycle it is usually 5to6days but is now 2days and at times twice in a month and is not longer 28days please what can I use to regulate it. Thanks