I Had A Transvaginal Ultrasound On Sept 25 Dated Me

I had a transvaginal ultrasound on sept 25 dated me 7 wk 4 day pregnant I had an ultrasound on Oct 30 dated me 12wk 3 day I have been given a due date of may 11 my question is could sex from July of caused my pregnancy is it all possible? What are the most possible dates for intercourse that caused my pregnancy? From online calculators i conceived in Aug I had a difrent partner in July and Aug so I need to know what mth I conceived