There is actually some academic research at the moment which aims to look at whether menstrual cycles have been affected by the lockdown and, if so, how. It sounds very interesting.
I would be inclined, though, to suggest that it's worth ringing the surgery and making an appointment to speak to one of the GPs.
Although women do have menstrual cycles of varying length, what is significant is when there is a sudden change and it does sound as though your cycle has changed of late.
Something you may wish to consider is whether there have been any changes in your weight, especially if you have lost weight.
There are other things which can cause a change in periods, so it's best to have a word with your GP this week.