when did i conceive

leshalj,

From your due date:
You ovulated around April 28.
Sex between April 24 and April 29 got you pregnant, most likely days: 26 or 27 April.

From your LMP:
You ovulated around April 27.
Sex between April 23 and April 28 got you pregnant, most likely days: 25 or 26 April.

It does look like your ex boyfriend is most likely the daddy.

The date you tested positive on or the level of the hCG hormone in your body is a vry unreliable method to determine the conception date. The earliest date you can get a positive pregnancy test depends on your ovulation date, not the sex. If you use the most sensitive test kit, First Response Early Result (not the digital one), it can be as early as 8 days after ovulation, 6 days before your next period is expected. With other kits it will be later and it differs between different women. Some women will only test positive weeks after their missed period.

Congratulations with your baby and take care.