Irregular periods

Has anyone had issues with really irregular periods and still had success? Mine have been irregular for over a year now and now my period is over 4 weeks late! I’ve done 4 tests during this time and all negative. I am now seeing the doctor for further investigation. I’m am gutted to say the least. I’m 37 in June and my older sister got early menopause so I’m freaking out! Feels like there is more chance of winning the lotto than falling pregnant now not to mention the worry about my health.