Here is a great link: http://mormon.org/family/ 
 
Also back in 1995 the Church leadership published the Proclamation on The Family. It is found here: http://www.lds.org/languages/proclamations/Proclamation_35602_000.pdf 
 
Does that help?

The LDS Church does believe that to receive exaltation the highest glory attainable to mankind and to inherit the same power and glory our Heavenly Father has one must be sealed for time and eternity in a LDS temple.  
 
There is nothing scripturally requiring one to have children or how many children on should have. These decisions are left up to the man and woman joined as one flesh in marriage, and the Holy Ghost is there to help guide them as needed.  
 
The Church does encourage young adults to not postpone marriage and children for career or other gains as we see the family as of the highest importance both physically and spiritually.  
 
Many members marry in there early 20's and start families while still finishing there education and starting there careers. They sacrifice this because they believe the most important duty on this earth is to raise a family and raise them to be righteous.  
 
As jett suggested it is a great thing to visits mormon,org or lds.com for official statements and policies regarding the family from the Church of Jesus Christ of Latter-day Saints.