Spotting on depo shot injection



Hello. I got my first shot April of 2018, for the first three months, I bleed pretty much constantly, I spoke to my nurse who reassured me this was normal, after my second shot the bleeding went away almost completely, I spotted maybe one or twice after that second shot, but then nothing at all. About 8 or 9 months later (after continuing to get the shot when necessary) I spotted for one day, then nothing again, today (at around 11 months on the shot) I have spotted again, very light, my question is, is it normal to go months with no bleeding whatsoever then randomly spot for only a day? Thanks x