Heavy bleeding

So my last period was October 20th I have done all the dr blood work with levels and repeated them they are rising. On Tuesday I went for a ultra sound and was measuring 6w1day. That would be correct since I ovulate late. Yesterday I stared bleeding pretty heavy so I called my dr and got another ultrasound. Baby is still in there but still measuring around 6w1-2days. Dr is not concerned because when it’s that little it’s hard to get a super accurate measurement. I am not bleeding today. Anyone else randomly get heavy bleeding and go on to have Healthy baby?? I have a 3 year old never bleed and have had 2 miscarriages this year so worried it going to end. Thanks for any experience!!