Hello, I Know The Exact Same Day I Ovulated And

Hello, I know the exact same day i ovulated and I took a clear blu test that said i am 2 or 3 weeks pregnant and the doctor will see that 4 to 5 weeks and I know I Can't be 5 weeks if I ovulated on the 15 of May. But my bf actually thinks that I am wrong and if I'm 5 weeks pregnant, the child is not his, and I know it's his cause I didn't cheated on him. Please help