This is getting frustrating

I got Depo last month and this period started on time but it was very light, like a regular tampon was almost too much. Very new to me as I've been using Ultra since I was 13. My problem is it's been 13 days and there's been no change. Almost like I'm shedding the same amount just much slower. I wouldn't consider it spotting since I do still need to have a tampon in or I'll ruin my panties within an hour. Pretty frustrating since I have a normal 28 day cycle and it's almost taken up half of it.