In the current scenario, you should take a serum beta-hCG titre estimation along with a trans-vaginal sonogram to come to a definite conclusion. If you have always had regular cycles, pregnancy
is the most likely possibility here. If it is so, you will not get a withdrawal bleed. Moreover, progesterone
is given to maintain pregnancy. Please contact your doctor after getting the blood test
and sonogram for further management. Hope you find this information useful. Wish you good health.