Scan then bleeding plz help!!

So I thought I was 6 weeks on Sunday based on my LMP which is irregular  but last week I took a pregnancy test and on Wednesday it should 2-3 weeks pregnant and was told to go for a scan today, so since 2 days ago I have been getting light brown mucus and today it increased went for my scan and it was and there was an empty sac measuring at 3.2mm she then said I wil do an internal scan she then said I look earlier than I thought so i must of had a late O, once I went home I started bleeding when I wiped but no cramps and on the pad it was brown, still here jut now and my HCG levels was 2000hcg. Has anyone else had this before and how long did this last