I had unprotected sex during ovulation and 3 days after had what I thought was the stomach flu, then a week later had bloating, belching, nausea and tender to the touch breasts. My basal temperature was way up 7 days after ovulation. I did not get my period and since then no major signs, just heavy full breasts that have continued since then and some food aversions like ice cream which used to be my favorite snack. My nipples have also darkened. It's been 27 days since ovulation but urine tests keep coming back negative. Can I be pregnant?