Is there a possibility I could be pregnant?

Patient: Is there a possibility I could be pregnant?I was 16 days late with my period and then started bleeding lighter than a normal period on and off for 2-3 days it was brown,bright red,pink in colour before this I had sore breasts, back ache, nausea, tiredness and some other signs of pregnancy I had taken two hpt both coming back negative and so did one at a doctors office since the bleeding stopped the symptoms and coming back and my stomach is going hard when I’m stood up what could this be?