Your worry is normal. But you can relax and there is no need to worry. Even though you didn't ejaculate, there is always a slim chance for her to become pregnant with your precum.
So, to be on the safer side, make sure your partner consumes an emergency contraceptive pill before 72 hours.
You can buy that from your nearest pharmacy. So, give her the pill as early as possible and have a blast with your partner as soon as possible.