Since you have always had regular periods and also based on your symptoms, you have good chances of being pregnant. In the present scenario, you can either repeat the HPT with a fresh early morning sample of urine or go for the serum beta-hCG
titre estimation for a better confirmation. This coupled with a trans-vaginal sonogram clarifies the issue. Please consult a gynecologist for a proper evaluation and further help. Hope you find this information useful. Take care.