I had sex on dec third unprotectd twice with my ex (please don't judge me) and he ejactulated inside me... then I had sex again on dec 4 (with my daughters father) and he didn't ejactulate... but I had my so called period on dec. 13 2011 that was very very light and lasted for 3 days and I usually go for 5 days kind of heavy... then I had sex on christmas with my daughters father once again and this time he ejactulated... I want to know what day I conceived my now 5 month old baby

Good luck with that.

Well... there's no way you'll know the answer to this one until you do a DNA test to be sure.

I want to know what day I conceived my now 5 month old baby
I assume the dates your are talking about are 2011..

Dates are all Best Guess, and the only surefire method is a DNA test, especially when the encounters are so close together.