Sex 11/5 took planb 11/7 lmp11/13 sex again 11/26 took 2pregnancy test both negative dec12 sex again test dec/17 got positive when did i conceive?

Too confusing: It is hard to follow your timeline. You can add two weeks from your last period and that is a likely date of conception. Given that you took Plan B and your cycle could have been a little off you will need to schedule a visit for a sonogram to accurately determine how far along you are and when you got pregnant.

End of November: This is a best guess based only on the information you provided and assuming a normal pregnancy. Since the test turned positive between 12/12 and 12/17, conception probably occurred about two weeks before that. This would correspond with sex on 11/26 but conception could have occurred up to 6 days after that date. When you get checked, blood tests and sonograms (ultrasound) can clarify this.