Could i still be pregnant, with a negative test 25 days after intercourse? i have a very irregular period, and am having symptoms.

Unlikely: But conceivable. Assume you are using urine test strips for hcg. If these symptoms continue or worsen suggest you see your ob/gyn doctor. Good luck.

Irregular menses: You haven't given enough details. So you had a negative pregnancy test 25 days after intercourse, presumably unprotected. However, you didn't mention your last menstrual period. So yes it's possible to be pregnant if your negative test was a while back. If you're concerned, take another test when at least 4wks have elapsed since last menstrual period.