PP cycle tracking - what gives?

I'm seriously so confused. I have been taking opk every few days since about 6 months PP. I BF and have been starting a very slow weening process. 6/29 I finally get a high fertility result, a few days later = peak fertility! We were so excited! 4 days after that I had a couple of days of light spotting, two days of nothing, followed by a day of a possible blood clot. Just to be safe, I took a few pregnancy tests which were all negative. Still no real period when anticipated. opk says high fertility again 7/23. 7/24 I have a heavy flow. 7/25 = very little spotting and another high fertility day. What in the world is happening? I know this can happen when AF returns, but really, this? I feel like I should just stock up on tampons, pads, OPKs & pregnancy tests. What was your return of AF like?