Dark brown discharge / bleeding

I’m on the depo shot so I don’t really have periods just spotting which is usually pinkish-red but this time it’s dark brown which I know usually means old blood. I’m almost due to get my next shot, which will be my third in total since giving birth, is this just a sign that my periods will probably officially end now? There’s small sticky clots like as well just a few sorry if tmi 🙃