Why am I still measuring @ 13weeks

I’m now 15w+5 and last night I went to er at 11pm bc I saw blood and instantly got scared because of my recent miscarriage in January I waited hours and hours to get an ultrasound nervous & anxious to make sure my baby was okay the nurse didn’t let me see anything or tell me anything so it made more nervous the dr comes in at 3am to say the baby is okay but measuring at 13 weeks which is confusing because I measured at 13w+1 when I was 12w+5 on June1st and my previous Scans we’re measuring up to date 🤔I think it’s bc the lady maybe rushed but they’re basically trying to push me back into my 1st trimester. What could be the issue ?