A small light leak while loading would not make negatives perfectly clear. With black-and-white negative film, extra light makes film darker after development, not transparent.

The key check is the film edge printing and leader:

• If the film has visible edge markings (film type, frame numbers, batch info) but no pictures, development basically worked. That points to a camera/exposure problem, often the film not advancing properly after loading. A clue is a dark/black section at the start of the roll from the leader being exposed during loading, with the rest blank.
• If there is no edge printing at all, the problem is processing-related: the film was not developed properly, the chemistry was wrong, exhausted, mixed incorrectly, or otherwise failed.

So the first step is to inspect the negatives carefully for any density changes and especially for edge printing. That will tell you whether to troubleshoot the camera or your developing process.