If I had sex on the 8 and found out I was pregnant on the 20 of April woulld that be two weeks prenant.?

Generally a pregnancy is dated from the first day of the last period. So most women are not actually pregnant in the first week or two. When was the last period? Did you have sex before the 8th? If so, how far before?

While you had sex on the 8th, there is no way to know for sure when you actually conceived. Many women will not get a positive result on a pregnancy test until about two weeks after; even more often not until a period is missed. However, some women will get a positive result as soon as about 8-10 days past ovulation.

My last period was on the 18 of march and yes I conceived on the 27 through the 1 of April

Your doctor or midwife would date your pregnancy from March 18 (your last period). This would put you about 4.5 weeks pregnant (gestational age). You could be closer to about 3 weeks pregnant going with fertilizational age, or actual conception. When you have a scan, this may change slightly.

If you think you conceived somewhere between 27 March and 1 April, the sex on the 8th of April would not make any difference as you would have already been pregnant.