Worrying can make your period late, so first off you need to relax.
To answer your question, anal sex itself can not get you pregnant, there is no connection between the anus/rectum/intestines and the reproductive system.
The fact that sperm ran down over your vagina does put you at risk of pregnancy yes.
However, you should always use a condom for anal sex as there is such a high risk of infection, if any of your anal bacteria caught in the folds of skin on hs penis, he could get a nasty infection, or if he put that penis into you, you could get a nasty infection.
If your period is already late, you could try taking a pregnancy test, if it turns up negative wait a week and try again. Or see your doctor.

You should be able to take a test since your period is already late, it really depends on the person. It will be okay..Dont be scared we have all been there remember that.

I think theres a really low chance... Sperm have such a long journey as it is in vaginal sex... It would have to be some really determined sperm to get you pregnant.

I mean, its not impossible.. I got pregnant using a condom( it fell off right before we were done), so not alot of semen got even in me, but I did get pregnant.

Like the other girls said, always use condoms.. You have to be safe.. And you can take an hpt if you'd like.

Good luck!

I dont think you are but you need to always use condoms and get on b/c