Why did I get pregnant now?

Been with my husband for 6 years. He has kids, I DONT. I just assumed something was wrong with me. We have a very active sex life so I can't believe that we were missing my "fertile window". I mean at least once a day type thing, usually more. I ended up with a BFP two weeks ago and miscarried last week. I'd love to try again, but its got me wondering why it took so long and if it'll take another 6 years. I realize only God knows, but has anyone else had this issue?