Your periods were regular so far, once in 28 days. You had cortisone
on the day you were expecting your periods. You did not get your periods. almost 6 days passed, that means now you are on the 34 th day of your LMP. You are having cramps. you did 2 pregnancy
test both were negative. Understand that the real picture of pregnancy test can be seen if it is done after 40th day of your LMP.
Calculate your self which is the 40th day from your LMP and do pregnancy test after that day to get the proper report.
Cortisone is very famous in producing menstrual disturbances, some time excessive prolonged periods
. So unless other wise indicated the use of cortisone to be avoided. Regarding cramps wait and observe