37 and expect #3 (youngest is 8)

Just got remarried in July '14. He has no children of his own. Lost one in May, never miscarried when I was younger. So my age worries me, but also my older cherubs, 11 yo DD and 8 yo DS. I worry about meds I'm on. And I worry about telling people...the kids, my ex (shouldn't matter, but he's unstable), my parents, my sister (she's due with #2 in May and I hate to take away her lime light). I'm happy, but trepidatious. Just looking for some words of wisdom.