Girls, hello! I have long-awaited pregnancy, at 4-5 weeks we didn't se…

Girls, hello! I have long-awaited pregnancy, at 4-5 weeks we didn't see the embryo, only PYA, and at 6-7 weeks we saw it but didn't hear heartbeat and hCG 552.4, who had such? I am very worried, is it possible that we miscalculated the due date, or will there be a heartbeat on week 8-9 ????