First iui

Feeling very discouraged. Had my first ultrasound on yesterday. Doctor figure I'm at least 6 weeks 1 day by my LMP. Once he started the ultrasound it measured me at 5 weeks 1 day. The doctor only see a sac. Nothing inside the sack. He feel he should've seen something inside the sac by how far along I am. He suggested I'm about to have a miscarriage or its an ectopic pregnancy. Only symptoms I have are tender breast, fatigued, stuffy nose, cramping. No spotting or bleeding. I read the story of Hannah in the bible and it gives me hope. I pray next ultrasound next week the doctor see something. Have anyone gone through this?