Could I be pregnant?

Hi I’m new on here and I have a Question my boyfriend and I have been trying to conceive, I started my period on August 25th and it lasted until September 3rd. My cycle lasted 28 days I was supposed to start my period for September on the 22nd and I have yet to start I’m five days late and I have swollen feet, toes, and ankles, swollen fingers I’m tired all the time I’ve had a lot of headaches I’m having some mild cramps but they’re just like in my uterus area I’m irritable but... I took a test today, it came back negative could I possibly be pregnant and my levels be to low to be detected on a home pregnancy test? Please help answer this we really want this baby