How to tell when my period is ‘late’ when I’m irregular?

Usually my cycles range anywhere from 38 days to 45 days, one of my periods came on day 49 a couple of months ago. I’ve seen the doctor about long cycles before and it’s no cause for concern, that’s just my cycle length. At the minute I’m on day 48 of my cycle and my period is still yet to come. About a week ago, I was experiencing all my pms symptoms, cramps, hot flushes etc and was so ready for it to come I was wearing pads to bed and during the day but nothing. I’ve not had unprotected sex once this whole cycle, I always use a condom and fill it up after sex to check for any leaks or tears. Obviously I’ve had a cycle this long before but it’s always a bit worrying so my question is, how long do I wait before my period is ‘late’ to take a pregnancy test? Or what else could be causing this? Obviously I’ve had day to day stresses but nothing severe enough to effect my period I would’ve thought. Any help is appreciated.