I agree the symptoms are very subtle but I did go off tea and alcohol (two things that I love) at about 3 weeks pregnant which made me think I probably was pregnant.
When after conception do signs and symptoms of pregnancy start? I can remember my sense of smell changing when pregnant with my first son but I can't remember how soon after conception this happened although I know it prompted me to do a test and after seeing the doctor I was 5 weeks pregnant...
The symptoms of pregnancy and when women feel them, differ from woman to woman. Some women know straight away that they are pregnant and some (astonishingly) don't realise they are pregnant until they are four or five months in! On average you'll probably notice some subtle changes between 4 and 6 weeks such as your breasts becoming tender or bigger and a heightened sense of smell and taste. With both my pregnancies I started getting morning sickness at 6 weeks and both times it stopped by 12 weeks. Good luck with your pregnancy and I hope you have escaped getting any morning sickness!