Hello yunsukchae
Welcome to HCM
There is a risk of
pregnancy even when someone ejeculates on vaginal area but this happens only in rarest of rare condition, because vaginal pH is hostile to sperms and for fertilization to occur semen must be at least near cervical os. But as you have mentioned there was only genital contact and no penetration and also you ejeculated far away from vagina, and also she is nearing her menstural cycle so there are practically zero chances of pregnancy. So be assured, wait for her cycle and there is no need of contraceptives. If you want to check then check from kits like Pregasure which are available at local chemists.
Hope I cleared your query
thanks take care