Could you still have herpes and test negative after 9 months?

Herpes: The serum test turn positive for herpes after about 12 to 16 weeks after exposure. If it has been 9 months since possible exposure I would say the negative test means you do not have herpes.

This depends on the : testing method, direct testing of lesion sites, can be negative if no active lesion is present. Blood tests just look at antibodies, that have formed, from potential previous infections.