Hello, I have gone through the query and understood your concern. A HPT performed with a fresh early morning sample should usually read well when done 3-7 days after the missed period. For a better clarification, you can go for the assessment of the serum beta-hCG titres. A trans-vaginal sonogram gives further clarity to conclude on the diagnosis. Please remember, self-medication is always to be avoided to prevent unnecessary complications. So, I would ask you to see a specialist for a proper clinical appraisal and plan further management. Weight disturbances, stress, infections and certain medications also change the menstrual pattern. Hope you find this information useful. Take care.