After 5 months

Okay so i had my period at the end of september , it did not come until 4 months later with medication ( it was a pill i had to take for 10 days after 3 days i was gonna get my period ) so after the pills finished i got my period 1-3-18 it was a very heavy flow & for 8 days, a month later i still havent gotten my period i am 15 days late but im having no sex so i dont know whats wrong , can i have some help ?