Hi Megan, I'm Katie. My story is pretty similar yo yours..I have a 14 month old (tomorrow) and we were NTNP several months ago....but I had not yet had my first PP period. When I got in in Nov, we started TTC and after a LONG cycle I got that POS at 10 dpo.
I started feeling sick for the next few days...boobs became sore... and then it disappeared and I started spotting. That night I miscarried just shy of 5 weeks. That was three weeks ago.
We ARE TTC this cycle but I have yet to O (not sure I will). Good luck to you!! I hope you get a BFP ASAP!!!