Humans are the only known carriers of gonorrhea.
Transmission is almost always by sexual contact.
Over 10 percent of men who are infected with gonorrhea do not know it. You may have had it and given it to your girlfriend. It doesn't really matter at this point who gave it to who. The important thing is that you both get treated as gonorrhea can cause lots of problems if it isn't treated. Your question also brings up a very important issue.