help!?

So last AF was 15th to the 20th of this month. My app says I am on my fourth day of my fertil window. I noticed in the shower last night that I am bleeding very lightly, also today. I have a tiny bit of cramping. Is this ovulation bleeding and cramps? I don't think I have actually ovulated since i got off the depo in April after being on it and not having a period for at least five years, so I have no idea what to expect. Besides things I've researched. I think it's to early for implantation according to my app. I'm confused, please help. I really hope this may be my cycle tc. All your help is very appreciated.