E.B.
My vote would be that breastfeeding is still the issue at hand. We conceived #1 in two cycles when I was 27. We conceived #2 in two months when I was 29. I miscarried, we waited until my cycles resumed normalcy, then conceived #3 in 2 months. Because I've always struggled with anxiety, and breastfeeding drastically reduces my anxiety, I thought I'd try to breastfeed while pregnant. After 8 months of trying, I weaned the "baby" at 33 and got pregnant the very first month I was completely done breastfeeding. I had had my period since one month postpartum (in spite of exclusive breastfeeding and fewer than 10 pumped bottles in his lifetime). My doctor calls me the poster child for breastfeeding-as-birth-control, as my "baby" was 2 1/2 by the time I finally weaned him.
Oh--and yes, for ANY woman, not just an older one, the likelihood of miscarriage goes down dramatically once a heartbeat has been heard, typically at a 12 week appointment.