Shan's TTC after m/c Wish

I'm 45 and husband is 55 and lots think we're crazy. We have 8 kids and 2 miscarriages. We want one more baby...hopefully a girl since we only have 2 girls both the older. We also have a granddaughter with another grandchild on the way. We've been married now 10 years and been trying for the last 18+ months to get pregnant one last time since the last miscarriage. I truly believe God will give us this child, but I just don't want us to be much older when she gets here.