So confused!! Help!!!

I had my first postpartum period on January 14th. I started taking opks on cycle day 11. I believe I got a positive on cycle day 21, February 3rd. If that's the case, I would have likely ovulated in the 4th, making me 7dpo today. I have been feeling very ill lately. I took an 88 cent test from Wal-Mart today (not fmu) and it was negative. I came home and took an opk and its really positive, more positive than the ones from cycle day 21. Any idea what could be going on??? I'm cycle day 29 now. I have no idea when to even expect another period since I've only had one. Please help!!