8dpo ... can I test? is it a waste of time?

Hi all 
5th month of trying and the wait gets harder every single month! 
I have on average 27 day cycle, pretty much to the day. Glow predicted my period would be 2nd march in line with that and the other apps I use but I ovulated a couple of days later than glow predicted ( positive opk). After I updated glow it is now predicting my period for the 4th march which would put me on a 30 day cycle?? 
Only symptoms I'm having is tiredness. Cervix has gone back to low and hard. 
No extra discharge. No cramping. No spotting. No nausea. Does all this mean I'm not pregnant again this month. When should I take a test confused when my period would be late now? Please help, going crazy.