5months after miscarriage

Arianna • married to my best friend 10.10.15❤️ TTC after a miscarriage💕
Is it normal to still have blood clots in my period and it comes every 18 days. My doctor had put me on Birth control that you can go months with out having your period. I still made sure to have my period every month because I was afraid of messing up my body. Now I'm scared my body is messed up and I won't be able to have kids. Has this happened to anyone else? What should I do?