I am confused. Please help me.

[Suranjana]

Hi. I am 22yrs old and i got my normal period on 6th feb. It ended around 13th feb. On 19th feb, me and my partner engaged into a little sexual activity without protection but as far our knowledge nothing went inside me because he didn't *** inside me. I was expecting my period on 6th march as per previous but since i didnt had on that day, we again engaged into sexual activity same as the last time without protection where he didn't *** inside me. On 12th march, 5days later, i had my bleeding with the first three days heavy vibrant red flow and today on the fourth day, less bleeding. I took a prdganews pregnancy test today and it was NEGATIVE WITH A DARK LINE BESIDE C kn the detection device. Now all i want to know is, this bleedjng is of my menstrual cycle i.e. is this my period? Or is this implantation bleeding? Do i need to test my urine again once mg bleeding stops? Is this 5days late bleeding ang sign of pregnancy? I don't wang to be pregnant. Please help. I am very scared and tensed. Is there any chance of me being pregnant? Is this my period bleeding? Please help. Please.