Because you have just started your period last
year, it is normal
for your menstrual cycle to be irregular. This means
for the next [average] 2 years after you first began your period, you could go a week, month, 3 months, 5 months, or even a year without your period. One time your period may last for 3 days, another for 7, and then for 5 days.
Usually [average] 2 years after you start your period, it will become regular.