How to differentiate between period and implantation bleeding?

Hi doctor,

My average menstrual cycle is 28 days. Two months before, I got my period on the 19th, and it ended on the 23rd. I had unprotected sex on the second day of my period. I do not remember whether the guy ejaculated inside me or not. As I was worried, I consulted two gynecologists. They advised me not to take an I-pill as I was in my safe period. So I did not take a pill. Next month that is, I got my period on the 20th. The bleeding was heavy with clots and lasted for three or four days. Last two days, the bleeding was light. This month my period is due on the 17th. I have mild cramps in my lower abdomen and mood swings (which usually occur when I am near my period). I do not have any changes in my breast size, no nausea, no morning sickness, no sense of smell, and no weight gain. I lost a few pounds, though, and no frequent urination, nothing similar to the symptoms of a pregnant woman. Was it an implantation bleeding that I got in the last month? I was worried about whether I was pregnant or not. I do not have any signs or symptoms of pregnancy. Will I get my period for this month? I am very tensed. If that was implantation bleeding, what should I do to terminate this pregnancy? And if it was not an implantation bleeding, was it a normal period, and what should I do to get my period on time? Please help me. I am worried.

Thank you.