7 week ultrasound no heartbeat

Hello ladies. I had to go to the hospital because i thought i had a really bad kidney infection. It turned out to be something minor but now im freaking out. They decided to do a transvaginal ultrasound just to make sure baby was in the right place and everything. Im "technically" supposed to be 7 weeks and 4 days so a heartbeat sould be noticable. But they told me they could find one. Now my periods are irregular and they told me to relax and that the baby could just be behind the date of what we actually think. Now they did tell me my hcg levels are where they should be but if they aren't sure that the baby might be younger im not sure if that is still right. Ik this is a long post and thank you for reading all the way through. Im just looking for ladies that have some insight and or went through the same thing so i can have some idea of what to expect. Or if i can have any positive messages and vibes (i had a miscarriage in march and i don't think i can handle another one). I wont be able to see my ob for another two weeks so im kinda having a mini meltdown.