Cycle length change, see a GP?

[TomRipley]

My cycle length has changed from a 'like clockwork' 28 day cycle to a 'like clockwork' 21 day cycle and I'm wondering if I should be concerned?

Background- had my third baby 18 months ago. Periods came back 10 months PP which is not unusual for me because of breastfeeding.
I'm still technically BF but I'd say it's at the very end now (every couple of days for a few minutes).
Apart from the shorter length they're a bit heavier but no cramps or other symptoms.
I never have suffered with painful periods so that's all the same.
Im 38 and up to day with smear tests, haven't taken prescribed contraception for 7 years.
What do you think?

Oh I'll add I have had two Astra jabs as I know there have been reports about the vaccine messing with periods but last dose was 6 months ago and have my booster next week.

We are threads like this before...
I can't understand people whose health measures never change, so I don't know why you'd think a simple change was something to worry about.
Evidently a lot of people do worry.
But odds are... doc will tell you it's just normal variation after all.