According to your wife's last menstrual period the gestational age
will be around 5 weeks 5 days,
the expected hcg levels in this gestational age are between 18 to 7,000.
so her hcg levels are in normal range only.
some amount of weakness, hypoglycemia
etc are common in pregnancy
let her start taking folic acid
tablets, vitamin supplements and mainly nutritious diet with enough rest.