While many women report very early signs of pregnancy, others never have symptoms. For most women, missing a menstrual period is the very first sign that they are pregnant. Nausea and morning sickness are also commonly among the earliest signs of pregnancy, as well as fatigue and exhaustion. Breasts may also become tender, similar to the way they feel before your period. Many of these symptoms usually do not appear until after a missed period when hCG levels are high enough to induce the first signs of pregnancy, often weeks after implantation.
The first appearance of the pregnancy hormone hCG depends on implantation, the attachment of the fertilized egg in the uterus. Implantation occurs on average 8-10 days after ovulation (range 6-12 days). hCG then first appears in the blood about 3-4 days after implantation, or at the earliest 10-11 days after ovulation. Before a missed period and positive pregnancy test, it is difficult to assume that certain physical symptoms are pregnancy-related.
No matter how many symptoms you have, the only way to diagnosis pregnancy with sufficient reliability is to have a positive pregnancy test.