Missing period

Ab
I stopped taking the progesterone only pill on 22nd July. My last period was on 13th April so I'm now 50 days late. On the mini pill I usually have periods but in May it never came. This happened in 2014 when I was on the same pill and it worried me so I stopped taking it. I remember my period coming back quite quickly afterwards but this time it hasn't. I had some light spotting the first couple days after I came off the pill . Do you think this is something I should be worried about? I'm not pregnant as I'm not sexually active. How long have other women waited for their periods to return ??