Measuring 2 weeks behind...

Today was a bitter sweet for me. Went in 2 weeks ago and only saw a GS and yolk sac. Went in today (8 weeks) and measuring 6 weeks instead of 8. This pregnancy happened immediately after my chemical last month so I wasn’t tracking my ovulation, I’m only going off my LMP which was 4/10... We did get to see a heart beat which measured 77 BPM, the OB said the heart probably just started beating like yesterday. We go back next week for another ultrasound. I’m thanking God for seeing a heartbeat at least but this is going to be the longest week of my life. 😓 Is there any hope for my rainbow baby??