Large Sac 5w

Anyone had experience with a large sac and it been OK?

I thought I was 8w (based on period) but based on when I actually tested positive measuring right at 5w 3d. She looked confused for ages and called in another woman to confirm as the sac is so big she wasn't sure if it was twins or just a big sac. Could barely see baby although there was a heartbeat so happy to hear that after going in for spotting. This is my 4th pregnancy (my son, 2 miscarriages then this)