5 days late

I'm five days late. I usually have a 31 day cycle. I was suppose to start July 21. I'm having some bloating and everytime I try to eat it's like I either can't or I feel like I'm going to throw it up. I took a pregnancy test yesterday morning when I woke up and it was negative. Is there a possibility that I still could be pregnant? Ive been trying for 3 months now and I'm starting to lose hope.