OK, let's do the math. The original image is 16:9. Or, probably if you took it portrait, it is 9:16.
If you try to take the two that are 9 and make it fit into 16 when it needs 18, then you are going to have a problem.
Perhaps rather than a picture, you could tell us the size of the frame that the sequence is set to, and tell us how you reduced the image to fit. It is just simple math, but we need the numbers you used to plug into the equation.