Empty sac at 7-6 days!! Any suggestions

Hi im supposed to have 7-6 days today i went to my first ultrasounds and the lady did vaginal she only saw the sac empty she said im pregnant but only 4 weeks what sounds crazy to me my last period was on 27 jan that was long time ago, i have even a belly all symptoms no bleeding, she told me to come back in 2 weeks that i might be behind that i think. Do you think i should get second opinion right away or wait those 2 to long weeks? This my first baby im 36 years and we got pregnant right away when we first try im very healthy so i hope just my baby is not ready to be seen or the place was not to advance for this early ultrasounds. I apreciatte your opinions 🙏🙏

To give update on this i did miscarried now at my 9 weeks it was blighted ovum it was natural miscarriage the doctor said i can try again in 3 months 🙏 Im ok now i have accepted that God knows what is for the best so i can't wait to try again 🙏🙏💫