Can I still be the pregnant?

My last period started on 3/11 and I still haven't started my next period Which means today is cycle day 41. I haven't had a crazy amount of stress and no change in my diet or excercise. My cycles are usually between 29-32 days long... I tested on cycle day 37 and got negatives (picture below). Should I test again? 
If I haven't started by cycle day 45 I'm going to get a doctors appointment to make sure everything is ok... :/