I had a very similar experience. My first child took two years to conceive. My second came to us after 18 months of fertility treatments. Lots of intervention, lots of medication, procedures..... Then I got accidentally pregnant while still nursing number two. I found out at 9 weeks that I was pregnant, then miscarried at 11. When I went to the ER, the doctor casually said, "Oh, yeah. This is fetal tissue." I still feel guilt about not having "wanted that one".