Had my period on jan 20 (4-5 days) had sex on jan 26 with #1 and took a plan b the next day. Got a period again jan 29 (3-4days) it was a little light. Then had sex on February 14 with #2 and took a plan b the same night. Didn't get a period after that or any bleeding. Then I found out I am pregnant and due nov 5th.

Get a DNA test after the birth... those are all too close together to guess.

Morning after pill is not 100% effective... nor is any form of birth control.

Doctors can only guess a conception date to a 4 week period. Medical science isn't good enough to be more precise than that.