If you didnt use a condom and not on birth control can you be pregnant?

It's possible.

If male ejaculated inside the female's vagina, then pregnancy is a possibility.

If he ejaculated outside (used pullout method) that chance would be drastically lower, but marginally still possible.

Other than that, woman has to be ovulating in the first place - if she does not produce an ovary (egg) no fertilization can happen.