What Are The Chances Of Pregnancy Post Non Penetrative Sex?

Hello... Today, me and my girlfriend were together, we were hugging and kissing and i was erect. Although i was wearing my underwear and track pants but i think i had released pre-seminal fluid and i did rub her vagina with my erect penis (only for 5 to 6 seconds), even with my clothes on and i think that the pre-seminal fluid might have touched her vagina. Also I did not ejaculate anywhere near or inside her vagina. Is there any chance that she might get pregnant???. She had her period on 9th of this month...I mean are there sperms in pre-seminal fluid and can they travel through clothes and make a girl pregnant??? Please reply asap...we re worried...