I'll try to help, but you might not find the answers fully satisfying. The bottom line is that there is a lot that isn't known about HPV. You should look at the following thread from just a few days ago: http://www.medhelp.org/posts/show/376638 As
you will see, it is essentially the same question you have, asked 30 years later. It is from a 50+ married, lifelong monogamous woman who might have acquired her HPV in circumstances similar to yours.
First, there is no doubt you have HPV. Nothing else causes the pap smear changes you describe.
Second, while genital intercourse, or at least genital apposition (without penetration) generally is required to catch HPV, hand-genital contact may transmit some cases. I cannot say whether it is ever possible to transmit the virus through the amount of moisture than might penetrate intact clothing. More likely, there were gaps in the clothing somewhere along the line; I suspect you were infected because there was a certain amount of actual skin-to-skin genital contact.
But the bottom line is that you will never know for sure. And it really doesn't matter. Somewhere along the line, you were bound to get one or more genital HPV infections. If not now, sometime in the future. It happens to virtually all sexually active people, except in those involved in permanent, lifelong relationships with partner who also never had sex with anyone else. And even there, a few infections might be acquired by unknown, nonsexual routes.
At this point, the most important two things are 1) to follow your provider's recommendations for follow-up and treatment of your abnormal pap smear; and 2) get immunized with Gardasil, the vaccine that prevents infection with the 2 HPV types that cause genital warts and the 2 most common types that increase the risk of cervical cancer. Undoubtedly you still are susceptible to at least 3 and maybe all 4 of those HPV strains. All young women should be immunized.
I hope this helps. Best wishes-- HHH, MD