Hello, I have gone through your query and understood the concern. Since you have irregular cycles and also use progesterone to induce a period usually, your ovulation status is questionable. This makes you safe and puts your chances of natural conception very low. Yet, even with natural regular ovulation, the earliest time to test for pregnancy is at least a week after the intercourse through an estimation of the serum beta-hCG titres. A trans-vaginal sonogram can follow after another week or two, if tested positive. This will help to estimate the age of the pregnancy and to locate the gestation sac. Hope this helps.