During the second week of pregnancy your ovary releases an egg into the fallopian tube. Once the egg has been released it must be fertilized within 12-24 hours or it will die and will be removed with your uterine lining during your next period.
Conception typically takes place between days 14-17 of a regular 28 day cycle. When the egg gets fertilized it is in the fallopian tube.
*Fun Fact:* Sperm can live up to six days long. Also it can take up to 3 days for sperm to reach the fallopian tube.
Right from the beginning of fertilization your baby's gender is known. Sperm carry either an X or a Y chromosome determining the gender.
X - Female
Y - Male
As soon as the egg is fertilized it begins to grow and the cell begins to multiply.
Once the fertilized egg has reached the uterus it implants itself into the uterine wall. Usually close to the fallopian tube that it had come from. A premature placenta also develops, which causes HCG to be produced. HCG (Human Chorionic Gonadotropin) is a hormone that keeps the uterine lining from shedding and stimulates it to grow.
You still do not feel much different than before.
Some books that I studied from are:
The Pregnancy Book - Everything you need to know from America's baby experts.
By: William Sears, M.D., and Martha Sears, R.N., and Linda Holt, M.D., F.A.C.O.G.
Your Pregnancy - Week by week
By: Dr. Glade Curtis, OB/GYN and Judith Schuler, M.S.
You & Your BABY Pregnancy - Your ultimate week-by-week pregnancy guide
By: Dr. Laura Riley, OB/GYN