Hey mamsh, congrats sa pregnancy! Based sa timeline mo, most likely yung conception was around late April to early May, kaya best bet mo talaga ay yung April 26 or May 1, those dates align best with 17 weeks na ngayon. But honestly, the most accurate way to know for sure is to ask your OB, they can pinpoint it better based sa ultrasound measurements, especially kung may dating scan ka na from early pregnancy!