Would an hcg of 60 be too low at the end of 3 weeks pregnant?

Likely not: At the end of the third week, 60 mIU/ml is usually within the normal range (however, specific number will depend on the lab). HCG is frequently used to assess the viability of the pregnancy - with the levels doubling every 48 hours in the early stages of the gestation. Thus, a single value is rarely clinically useful other than to identify that a pregnancy exists or existed.