If you only have a set of JPEG images, then there is no information about positions of each image slice in 3D. Slicer assumes that they should be stacked on top of each other with a constant spacing. Is this a correct assumption? Or they should be arranged in some circular pattern?
As Steve asked above, could you post screenshots of how the images should appear (e.g., screenshot from your OCT imaging console) and how it appears in Slicer?