Found out I was pregnant when I "miscarried"

So I didn't know I was pregnant. I had taken one test the day after my period was due.. got a faint positive and then two days later got a negative. I tested four other times and all negative. So I thought it must of been an evaporation line. Well 13 days late still no AF all a sudden I got super bad cramps and I went to the bathroom and I passed some tissue. According to my doctor the "tissue" I passed was most likely the fertilized egg that detached from my uterine wall because I'm breastfeeding and the contractions breastfeeding causes must of made it so the egg unattached or never attached that's why I got the faint positive. I honestly don't know how to feel because we were trying. And since we thought we hadn't conceived we decided to take a break from trying... I don't even know if I even technically had a miscarriage. I'm just so emotionally confused..