After I had a miscarriage on February 18, 2015 I had my hcg level tested again on Thursday March 5, 2015 could I possible be pregnant?

Too soon to test. Even if you got pregnant after the miscarriage, testing on March 5 was too soon to provide a meaningful result. In particular a negative result would not rule out pregnancy. If you do not get a period by March 25 or, do a home pregnancy test if you have any symptoms of pregnancy.