Is it possible that a 17 year old girl who was recently diagnosed with gonorrhea has had it for four years without knowing?

Unlikely: There are cases where a person has carried GC without many symptoms, and the source and timing was difficult to confirm.However, eventually the germ can move to areas that become dramatic in their impact. It can cause blood poisoning,joint infection, dramatic abdominal infection.Male contacts during that period would likely to be symptomatic.