It has been 4 days since you had sex. Pregnancy symptoms usually don't start until 14 days after sex. What day of this week is her period due? Today? Tomorrow? Saturday? Her period might not even be late and her stomach might hurt because of her period.
Betcha condoms sound like a good idea now, huh?
More than likely she was not ovulating when you had sex. No ovulation = no egg. No egg = no pregnancy chance. Women USUALLY ovulate about 14 days before their period. If her period is due this week, her most fertile time has passed.
That does not mean pregnancy is totally out of the question. You should always (ALWAYS) use protection.