Gestational sac measuring at 8mm

My gf has irregular cycle and haven’t had a period in over 4 months- so had an early scan to determine how far along She is and Wehave been given conflicting results. The tech lady said 4-5, the nurse said 5-6 and Gp saying 3-4.

Ps: no fetal pole was detected.

Just praying all is well 🙏🏾