My due date is November 20th. On February 1st I cheated and had unprotected sex with my ex boyfriend but me and my current boyfriend has been having unprotected sex almost everyday after that I know my first missed period was in march, if I can remember correctly I had a normal period in February

It's IMPOSSIBLE to calculate an exact date... even if you only ever had sex that one time... ever... it could still be a week off... relying on Dr's estimates based on due date only get you to a plus or minus two weeks... that means an ENTIRE month is the window. SInce you don't even have that... you can be even further off with wild guesses.

IF you slept around that month... you will HAVE to have a DNA test to figure out who the lucky dad is. They will both be pleased they are both in the running.