Welcome to the forum. Thanks for your question.
My first advice is to not overreact. Nobody wants genital warts, but they should be viewed as a minor inconvenience, not an important health problem. As you may know, almost all sexually active persons experience one or more genital HPV infections, and up to 25% of all persons have genital warts at one time or another. The frequency of HPV or warts is poorly correlated with no. of sex partners or other indicators of high or low risk for STDs, so infection does not mark someone as "promiscuous" or otherwise unusual in their sexual lifestyle.
It is very unlikely you acquired your warts from your girlfriend. As a virgin, it is unlikely she has HPV. Also, genital warts typically appear 3-12 months after exposure, sometimes as long as two years, and they are rarely transmitted by oral sex or by "grinding" through underwear. Assuming you have been sexually active in the past, you should look to past encounters as the likely source of your warts.
As for the chance you have infected her, that's also pretty unlikely. Oral infection with the wart-causing HPV strains (mostly HPV types 6 and 11) is uncommon. (Showering after sex a month ago probably made no diffrence in risk.) It would make sense for her to keep on the lookout for oral area warts, but I doubt anything will show up. However, I would recommend she speak with her physician about immunization with Gardasil, the vaccine that effectively prevents infection with HPV 6 and 11, and also with the two types (16, 18) that cause most cervical cancers.
As for your own infection, once warts respond to treatment (or go away on their own), if they do not recur after a few months it is safe to assume the infection is gone and will not be transmitted in the future. It is true that HPV DNA may persist for life, but usually does not reactivate to cause future disease or transmission.
See the thread linked below, plus others linked in that one, for more detail about all these issues and others related to genital HPV. In the meantime, don't panic, stay mellow, and don't make this a bigger deal than it is.
Best wishes-- HHH, MD