Implantation or period bleeding?

Hey there, so I’m currently 5 months pp and haven’t gotten my period back yet. We had unprotected sex once about 2 weeks ago and I’m about 11 dpo according to cm that I was having which is the only thing I could go off of right now. So that is a hit or miss guess but this morning and right now when I went to the restroom and I had this and it was even lighter this morning. Could it be implantation or my period finally starting? It was more brown this morning but still light and watery..?