Incidentally, did the doctor give her a due date
? You can count back 266 days on a calendar
from the estimated due date
and get an estimate conception date, or use a conception calculator online. From you saying 8 weeks 6 days on June 15, I get conception as being on April 28, which makes plenty of sense given you having sex from April 22 to 25. (Not only is there the margin for error mentioned by the doctor but also, sperm can live up to 5 or 6 days in a woman's reproductive tract.