Period changes after first baby?

So I was super regular when I had my first (although it still took us several months to get pregnant).

Now my LO is 2 and we started trying again, and started tracking periods and ovulation from past 6 months and I am noticing fluctuations. My cycles are 26 day long, but 2 months ago it was 22 days, and this month 28!! I had never had such a short/long cycle. And in these cycles, I ovulated at 11 days, also very early than my usual 12-14.

It is making me very nervous!!

I'm 31 now, and was 28 when trying for first.

Is this fluctuation normal? If not, could it be due to body changes post baby or age??