Can a ultrasound show that you aee pregnant at 2 weeks and 5 days?

Not yet. The earliest sign of pregnancy detectable by ultrasound (gestational sac) is usually visible around 4 weeks.
No. Technically, the timing is such that (if pregnant), when you're due for your 1st missed period, you're probably pregnant even though a urine test may be negative. This corresponds to about "4 wks". And yes, you weren't pregnant the first two. An us 2 wks later will show something, but that is technically "6 wks" (2 wks after first missed period).