So confused

Happy momma of a princess with a angel baby 😇

At my first prenatal appointment I had a pregnancy test done to confirm my pregnancy. My doctor felt around my stomach and said it feels like six weeks. Then she done a vaginal to feel for my uterus and told me it feels like eight weeks. I went in to the ER for horrible stomach pain and they done lab work and a regular ultrasound and a vag ultrasound and the doctor ER told me I was six weeks and three days. She told me I conceived December 16 which is very confusing. My period was December 10 and went of on the 11 I don’t do ovulation tests so I don’t really know when I conceived. I have irregular periods. And I don’t know which doctor to go by. I have my second obgyn appointment on Monday. The reason I asked because with my daughter I was high risk and was told she was measuring a week a two behind. Hoping my second appointment is more clearer. I am just going by the scan from the ER. The ultrasound tech heard my lil beanie baby heart beat and I told the tech I am feeling flutters when I am laying still at night and I know it’s not gas.