1 and 1/2 day period?!

Was suppose to start Friday (hpt was negative this morning). Stressed on Sunday and then minor brown spotting (I don't usually spot brown before). AF started Monday with only medium flow. Today was light. No cramps except a week ago and were so light they could have been mistaken for gas. This is not my normal cycle for bleeding or cramps. Progesterone test confirmed ovulation. Has anyone with regular cycles had a one day cycle before? Any diagnosis or thing I should look out for? It just does not feel like I am on my period at all.