ya, I think you should talk to your mum
Firstly, don't worry,
it is normal to have an unregular cycle since you are young.
it takes some time for the body to set the cycle,
some people take a few months, some a few years
and some people do not get their first m until 20years or older
every person is different
so you don't need to worry,
you are normal since there are many other people who have the same thing happen
but i suggest you go to see a doctor to make sure every thing is ok,
just a general family doctor will be enough