Is there a chance i could still be pregnant?

Erika • Happily married to my best friend, and the love of my life. TTC. we serve Christ above everything.
I was originally suppose to start my period December 27 (today) but i started bleeding on Monday the 22, it only lasted 3 days, and it wasn't as bad as my normal flow... My breasts are tingly and sensitive, i have lower back cramping, and regular cramping...also a little more nauseated. But i took a test today (my expected period just because i don't think i had my period) and it came out negative...when should i test again? Could i be pregnant? Anyone else have this? Thanks