Hi docs can u help re blood sac

Hello, i had a mic in april and found out im pregnant july6th had an early scan done on fri and sac and yolk seen was 5+3 sac measured 10x6x14 but there is a blood sac under baby which measures 17x7x17 ive had no bleeding below though am expecting some from when blood goes, can u tell me more about it as im still in the air of what it is or whats going to happen, i have to go bk on 28th for rescan x