Look at the film via black light. Do you see darker streaks stemming from film sprocket holes? Could be caused by improper loading or unloading of film or improper developing.
Anyway, to rule out camera light leak, procure a tiny keychain flashlight that stays on when switched. Insert lighted flash light into camera and close the back. Now retire to fully dark darkroom. Sit with the camera a minimum of 20 minutes, This time allows time for your eyes to dark adapt. Look at the camera from all angles. Light that leaks in, also leaks out.