NEED ADVICE!!! Implantation bleeding???

Hi so I am 3 days late from when I should have started my period on March 16th. I am having all of the usual period symptoms I get such as cramps and mood swings. I had sex March 6th and March 14th with protection. I have taken five pregnancy tests and they have all been negative. I am not on birth control but I do have PCOS so I have had problems before. So this morning I woke up and I had bled through my shorts and was bleeding a lot and it was pretty much dark red so I assumed I got my period. Later on I slowly stopped bleeding.

So the first picture of the tampon was taken at around 8 pm today. ( This was still not as heavy as it was this morning.)

The second picture was from 20 minutes.

I’m really stressing out and I’m concerned that this could be Implantation bleeding.