Late period after Northisterone?

I took Northisterone (period delay tablets) back at the end of August and got my period a few days after taking them. Got my October period as normal, was three days late but pretty heavy and painful. I’m now 6 days late and haven’t gotten my period yet, no symptoms really of PMS. Just wondering whether anyone else has experienced this and whether Northisterone has messed up my cycle?

I came off the pill in April (not trying to conceive) and use condoms. Have taken two pregnancy tests, both negative. I had irregular periods before the pill but they have been fine up until now since coming off the pill. Wondering whether they’re starting to get irregular again? Anyone else had this problem?