Help! Brown discharge no period

Hey! Can someone tell me I’m not crazy and could still be pregnant?? I had dark brown discharge 4 days ago that eventually turned lighter and I only ever saw this when I would go to wipe. My period was due two days ago and I’ve had zero spotting since and had a negative urine hcg tonight. My boobs hurt and I’ve been nauseous but other than that, no cramping or sign of a period. Anyone shed some light? My OB wants to do a blood test tomorrow but part of me doesn’t want to waste the money....