No baby in sac, should I be worried? 🥺😭

I went to hospital yesterday as my heart rate had slowed to 20 and was getting very ill. They did a check on baby to make sure all was ok in that respect but all they could see was a sack? Is this normal at this stage? The Dr didn't say much and just said we'll take bloods again on Friday and another scan in a weeks time to see if there's any progression, what does that mean? It was 2 in the morning and lots was going on around me, telling me lots in regards to my other health issues hooked up to ecg, echo on my heart, I was so numb there was no baby and so tired from everything else I couldn't even bring words out my mouth to ask about anything. They tried to say I was 5 weeks or should be but I know with my longer cycles I ovulate later and this making baby smaller and less weeks I think? My lmp would base me at 5 weeks 5 days but if I work it out from ovulation I'm 4 weeks 3? Any words of comfort or advice would be amazing ladies 😩😩🤞 Really thought I was getting my rainbow 🌈 😭😭😭