First ultrasound today

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And I thought I would be 7w3d. They determined I'm 6w1d with a heartbeat of 74bpm which seems low from what I see online but also reading stories of the fact that baby's heart just recently started beating. Supposed to go back in 2 weeks but now I feel sad. 3 prior miscarriages before 9 weeks. Any positive stories similar to mine? Thanks ladies :)