Periods are taking longer to come, is it because of under eating/over training?

Hi,

Current stats: 53kg, 5'3". I have been on a cut since last July went down to 53 from 58kg. Current routine is running and weight lifting. I average around 1600 cals a day. My weight loss has kind of stagnated too, so i was thinking if I should go even lower, around 1200 cals a day.
My goals are abs and it seems bf% should be low for that so I was cutting.
However my periods over the last two months have happened after very long intervals (instead of the usual 28) and also very less amount of blood. Could this be concerning?
I weight lift around 4 days a week(total 5 hours) and run around 10-15kms a week total.