Dating conception

i kno this sounds really bad but i eed to ask someones advice an medical opinion. i ad a period around the 4/5 th april n was due on on the 3rd ov may but didnt come on, i ad a scan an they told me afta measurin the baby tht i was nearly 5 weeks gone. i desperatly need to no wen i concieved as i slept with 2 different men around 1 1/2 weeks apart. wen they told me i was 5 weeks gone did it mean my baby is 5 weeks old or i was 5 weeks pregnant? if im due around the 9th jan 09 cud u tell me wen i concieved please i worked t out as b4 my last period if my scanmeant my baby was 5 weeks old