Period length and pregnancy

I started my period at 13, and of course when it first starts its everywhere but as i got older it regulated and through highschool was about 5-6 days long and 3 of those days were usually pretty heavy. Well for the past several years it seems like my periods have been a lot lighter and shorter than they use to be like 3-4 days in length and usually only 1-2 of those days being heavy. Is this normal? Ive had 3 miscarriages in the past 2 years and im wondering if it has something to do with my uterine lining not being good enough.. has anyone else had this problem? My doctor told me i might have a progesterone problem and im not sure if that effects your lining or not? How long do yalls periods typically last? Anyone else with short periods have problems carrying? Everytime ive tried to get pregnant it has happened without a problem and rather quickly i just cant seem to maintain the pregnancy?