Due date question

So based off my last period my due date is March 1st however when I went to my doc to get tested as I kept getting negative pregnancy I still tested negative. She did bloodwork and it came back positive. I went back two days later and my levels confirmed I was pregnant. Because of my low levels she pushed my due date to March 26th. My question is what is my actual due date. I would think it’s March 1st?