I had sex on march 14-how soon can i take a pregnancy test if i don't really know when my period was due? also when can you see anything on an ultrsd

See below: Pregnancy dating can be confusing. The "gestational age" is usually the number of weeks since last menstrual period (lmp). If you have a normal length cycle and conceived on 3/14, you'd be about 9 weeks 5 days based on standard dating. Most home pregnancy tests should be positive by then. Transvaginal ultrasound can see a sac by 4.5 - 5 weeks but may take longer to see the embryo.