Somewhere in september 3!!!!!
It would have been somewhere between 3 1/2 to 5 1/2 weeks ago. No one can give you an exact date, not even a doctor. If you had more than one partner during that time then even though it must be hard you will have to wait until baby is born to do a dna test. We are all here to help, support and give our best advice but none of us can give you an answer to this question.
Take the first day of your last period and count 14 days. That will give you am estimate but only if your cycles are 28 days long
You have posted this soooo many times. We don't know when you conceived. If you are having paternity issues you need a DNA Test.