I had sex with my current boyfriend April 3 through the 8. we split up then I ran into an old friend and had a one nighter with him April 25 I think.. I honestly can't remember if I had a period in April I don't think I did. My due date is jan 18. Who can be the father. Pleasehelp

Since your due date is January 18, the most likely date of conception would be April 28. However, this is not guaranteed and you will need a DNA test for proof of paternity.