How high is the chance that I'm pregnant? I'm scared?

[ToriAka]

So I had sex with my boyfriend a few days ago, it was my first time. I have a latex allergy and I forgot to tell him, so we couldn't use the condoms he brought. We decided to not use one... I know it was a stupid idea. But it's too late to change now.

He did pull out before he came, but some of the sperm got onto my inner thigh, and now I'm hella scared.
I take birth control so I SHOULD be safe, but I'm afraid anyways...

So I wanted to ask, how high is the chance that I'm pregnant, even tho I'm taking birth control?