What Could Cause Delay In Periods?

I am having sensation like i am going to get my period, but I haven't got. I was on letrozole and duphaston last month and had hcg injection on day 14. Today is day 32. My stomach feels heavy and I had pain in my nipples for the past 15 days. Is the sensation like having a period is a sign for an impending period or is there a chance for me being pregnant