I’m a female, 13 almost 14 years old. The first time I got my period was Easter Sunday 2019 and I was relieved because I was starting to worry I never would and it was a normal period lasting 7 days. But I haven’t had it since and I don’t want to tell my mum. What could be wrong?

It is absolutely within the normal variation to have your first period at 13 (even going on 14).  It is also very normal to have quite irregular periods in the first year or so.  However, it is now about 4 months since your first period, and that is a bit unusual – I would say if you had periods every 2 or 3 months for the first year it would be more “normal.”  You could certainly wait another 1-2 months to see if you get another period, or you could make an appointment now to see a nurse practitioner or doctor.  It is possible that you have something going on, likely not serious, that is causing this variation in your periods.