What Causes Delay In Menstruation Other Than Pregnancy?

i am 29 years old, menstrual cramp when its about that time, in sept 2013 period was late by about 47days, in october no period, next period came exactly 60 days after the last one in november - spotting for 2 days,3rd day heavy flow, no period in dec, jan1st had a normal period that lasted 4days and up until now-none.

but i still get the regular cramp, bloating and all that.

did had a previous salpingectomy in 2007.

what does this mean? i have never had irregularities in my periods ever before, not even after my surgery(right tube was removed).

and i am not pregnantnow, had a baby in 2011. what does it mean?