Breastfeeding and period

So I am 6 months pp. I’m ttc number two. I have a period back. I noticed my cycles are further apart than before. They used to be 28 days now they are 30-35. I ovulate later in the cycle which is different than before. Anyways. I had my period this past cycle however I’m about 10 days past and I’m spotting brown discharge I haven’t ovulated this cycle yet. I’m day 16 right now. Is it normal to spot like this? It’s reminding me of the implantation bleeding I had with my first. I took pregnancy test it was negative and my opk was negative as well. Advice. Help?