You were dry-humping and you cumed and soaked her she had on jeans and a thong you had on shorts and boxers a week later she felt nausea and had a headache is she pregnant?

She may in fact be pregrant, but you didn't do it. Sperm can swim pretty well, but that would be like you swiming the Atlantic Ocean. Any time you have unprotected sex you can become a Dad. The chances just vary.