What Causes Heavy Bleeding And Clots During Menstruation?

we have been trying to conceive for past 4 months... I started planning in May and since June my menses are late ... one week late in June -- july was normal 4 weeks - august was 2 weeks august 29 late and I got sick (flu antibiotics etc) nothing in september and then again on October 21....2 days too many clots and heavy bleeding n now normal...was I pregnant? or is my body just getting used to intercourse and the period will be normal soon...