First ultrasound, help!

According to my last period, I am 6w5d pregnant. Today I had my first US and there was only a sac. No yolk or fetal pole. The doctor has me measuring at 5 weeks according to the US and scheduled me for another one next week. He also took blood to find out my HCG levels, but I won’t know what they are at until Wednesday.

Has anyone had this happen?! Trying to hold on to hope that I am just not as far along as I had thought (even though I tracked everything including ovulation using opks). I need some piece of mind. Please share your experience or leave some hope. First time pregnant and we want a baby so bad.

Thanks y’all!