Bleeding from the penis is not an indication of getting someone pregnant. There are actually no signs that you've impregnated someone right away.
Was it her blood on you or your blood? Likely her blood. Which means she either was A. a virgin and you broke her hymen which causes her to bleed or B. she started her period. (or she could have had an abrasion during sex that bled).
Think you are okay and I would not worry. However, it is not wise to have unprotected sex. This is how unwanted pregnancy happens. She'll hopefully get her period and if not, she needs to take a test 2.5 weeks after this sexual episode. And remember that condoms protect you against std's as well. get into the habit of using a condom.