I have an irregular period. Last year, I only had 3 cycle. This year, my 1st cycle was in May, 4th.

End of June to early of July, I have been experiencing sore breasts, back pain and fatigue. Thought my period is coming, so i drank a lot of ginger tea. Unfortunately, AF is not coming.

On July 7th, I decided to take a PT. After about 1min, I saw double lines. And hey, that was really unexpected. I took several tests again on the same day, and the day after. All appear to have double lines. Faint, but visible. Also took the digital pregnancy test, and it showed pregnant 1-2.

Yesterday, I had my first appointment with the Doctor. At the registration counter, the nurse said I might be 11wks pregnant according to my 1st day of period. On the scan, the Doctor discovered that I actually not 11wks pregnant, but still at my early stage of the pregnancy.. maybe around 5 weeks. And according to my scan, the Doctor said she saw nothing but a sac. Only sac. And she also said that I might conceived late due to my irregular period.

Question;

1) can someone tell me when I actually conceived? On which date?

2) is it normal to only see a sac and nothing else at 5weeks?