Implantation or period? Help

My periods are fairly irregular but this month I was 2 days late (I think) according to glow last month I was a day early and a while back I was 6 days late so it's not uncommon for my periods to be all out of wack. I think it could be implantation because it's lighter than normal periods (but not spotty) but the I had the usual PMS Symptoms plus the SEVERE cramps.