10 days late

My average cycle is about 30 days but this month it was 40. I had been feeling crampy and super tired for the past week but af never came. Until Monday, 10 days late and not like a normal period. I am 22 and have never had an irregular cycle before. A few weeks ago I had brown/blackish discharge that lasted about 3-4days on and off. And at the time I had no idea what could be causing it. Is there any way this could be pregnancy? My husband and I are definitely open to having children anytime now, just not quite sure what is going on with my body and wasn't sure if/when I should see a doctor. Thanks!