empty sac at 7w * after ivf * worries

hi all, had my first scan yesterday at 7w, didn’t get to see what we were hoping to see. dr could only see an empty sac with nothing inside. up to the scan i have been having dark tests everyday, not many symptoms other than being tired, minor cramps on and off and some nausea that’s only resulted in actual vomiting maybe 2 or 3 times since finding out around 3w5d. this scan finding has came as a massive shock as i haven’t had any signs or symptoms that have pointed to something being wrong. dr told us to come back in a week to get another scan so they can “double check” if they can see anything at that point - i will be 8w1d by then. she explained to us that right now she can’t tell us it’s definitely a miscarriage but also can’t rule it out either as she’d expect to be able to see at least something at this stage. because we did ivf for this pregnancy, it’s not possible that i’m earlier than i think so that’s not a possibility for why we can’t see anything unfortunately. i’ve had zero bleeding this pregnancy, not even a spot. my worry is - could this all be happening because they only had me on the vaginal progesterone from 2 days after my egg collection to 9 days after my transfer then had me stop it (a total of just 2 weeks on progesterone)? as i’ve been reading it’s standard for ivf clinics to have you on it up until the 8th to 10th week of pregnancy, but some people are on it right up to 16 weeks? i can’t stop worrying that they took me off it too soon and that’s why i’m now going through this 😔