When is the first day I got pregnant need answers

March 1 , 2 , 3 , 4 , 5  are my period days I have a 27 day cycle march 10 -15 Are my fertile days
​I found I was 5 weeks and 5 day pregnant April 9 
​  I had sex feburary 25, 26, 27
I didn't use condoms these days in feburary
 
March 7,10,11,13,14,15
I didn't use a condom  Juss only on the 10 and 15. The rest of these other days I used condoms
​So when was the first day I got pregnant is what I'm wondering . 
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