Your period started on October 24. You had sex on day 9 with your ex and on day 10 with your boyfriend.
Normally you will ovulate sometime between days 11 and 16 of your cycle. Sperm can remain viable for up to about 5 days.
It could be either.
It is unlikely that having sex prior to your last period would get you pregnant. You are unlikely to conceive having sex within about 10 days BEFORE your period. The egg is only viable for 48 hours after ovulation so it would NOT be viable.
You also would not have a normal period if you were pregnant, although there can be some bleeding.
Don't focus on the due date or the estimated gestation - they can vary.
You need a DNA test. There's no other way.