What Does Delayed Periods With HPT Negative Indicate?

hello my fiancé and I are trying to conceive. My period has been pretty regular. Tthe first one was 27 days. The last one was 35 which came on the 1st of march and today makes 40 days since. I had sex on the 20 because I was told I probably ovulate late. I did a home pregnancy test 30 days but it was negative. I haven't tested since. Could I be pregnant. I am 24. 5.2'. 167 pounds. Only grade 2 ankle sprain 2 years ago.