First, I will try not to be preachy, but the "pull out" method is NEVER a good idea. There are plenty of options (free no less) that you can use for safer sex. Contact your local womens clinic (often Planned Parenthood) They literally give out condoms to anyone who asks.
Now, onto your question. The mere fact that his ejaculate was on your pubic hair doesn't necessarily signify pregnancy. However, men have what many know as "pre-cum" or rather sperm infused substance prior to ejaculation (or orgasm, or cumming... etc) That alone is enough to get someone pregnant. Hence why the pull out method is a joke. A non-incriminating way to find out if you are pregnant, is to buy a preganancy test from almost any store (Walmart, Walgreens, Target etc.) and follow the instructions on the box. Otherwise visit
http://www.plannedparenthood.org/findCente
rProcess.asp and find contact information there. Often there are people you can anonymously call to answer your questions.
I hope this offers some help. And please, invest in some condoms!