Last Period Was Nov 25th. Still Havent Started 16 Days

last period was nov 25th. still havent started 16 days late negative test, spotted for a day like 3 days ago. could i still be pregnant? Cant really tell if my breast or darker because i had a baby 8 months ago so there still the same. i have really bad back pain. nausea. everytime i eat i feel like im going to puke.