The investigation is dragging on and on. Is there anything that I can do to speed up the process?

The textbook answer is that a military accused does not have a right to a speedy investigation, meaning there is no official right to require the investigators to complete their investigation or for the command to make a decision about what to do, if anything, based off an investigation.  The other side of this issue is that investigations tend to drag on when there is not someone actively advocating for resolution. All cases are unique.