A due date of November 6 indicates your last period started on January 30.
If so, it could be either.
You had sex on day 9 with "someone" and day 14 with your boyfriend. Sperm can survive up to about 5 days. You normally will ovulate between days 11 and 16 of your cycle.
Just as a guess, I'd say "someone" has a better chance. The sperm would be "ready and waiting" when you ovulated.
You need a DNA test. Good luck.