What should my hCG levels be each week?

Wide ranges. There is wide range of normal levels, by week, check the site below: http://www.Babymed.Com/hcg-level-in-early-pregnancy.
Varies by individual. Every person's levels are different. You can find tables online that will give you a range of levels by pregnancy week. Also know that the levels peak between weeks 10-12 and then decrease somewhat. In early pregnancy your levels should roughly double every 48-72 hours.