Utz Vs. LMP

Hi mga momshie! Ask ko lang po kung may nakaexperience na po ba sa inyo ng almost 3 weeks discrepancy between your lmp sa utz? Kasi po if base po sa lmp 8 weeks almost 9 weeks na po ako dapat but on my first ultrasound, my ob found out that i am only 5weeks? Medyo nababahala po kasi ako kasi i had an experience of miscarriage and nakakatraumatize po talaga. Thanks in advance for answering my question. God speed!!