I had sex on Feb. 6th and came on my menstrual cycle Feb 10th. I also had sex Feb 26th at 2am. When is the most possible day I conceived?

Most likely the sexual encounter on Feb 26 since you had a period after the encounter on Feb 6th. But it is possible that the bleeding on Feb 10 was not a true period. So it really could be either date.

Is this a matter of paternity? Obviously the child has been born since you did conceive sometime in February. At this time, if it's a matter of paternity, it would be very easy to do a paternity test. All we can do is guess.

True but my menstrual are regularly , I know for the month of March I suppose to came on March 10 but I didn't , I had little bleeding on the 19th could that have been implantation bleeding ?

And yes it does in a get a home dna test

As Alty said, the most likely time frame is from the encounter on the 26th. Most often you would not ovulate right before a period as it is ovulation that sets the timing for a period. Not everyone experiences it, but yes, the slight bleeding you had on the 19th may have been due to implantation.

A DNA test will give you the certainty that you require however.

Thank you so much I appreciate it