Age 39 and am going thru 3rd miscarriage in a year

Can anyone give me some positive reassurance? I am currently going through my 3rd miscarriage in a year, I really need some positive stories or ideas on how to get a healthy pregnancy, we want one last baby. Our last 3 miscarriages were so hard and they think it’s my age because we have two little girls the last one was born in June 2019. Is there any ideas how to stay pregnant with a healthy baby. We were doing the progesterone suppositories but that must not have been enough. Please help with anything positive or ideas.