Help pregnant?

My husband and I have been ttc for 4 years. I was suppose to start af on 6/15 my cycle is uaually only 28 days long I am now on cd 33. I have had really sore tender breasts for about 2 weeks now had diarrhea on and off for about a week and had heart burn for 3 says on and off ive also been nauseous only at night time for the last 3 nights never vomited.. im really scared to take a hpt because the last 4 years they all have come back negative. Help me has someone experienced this? What were your results?