What Causes Early Periods With Heavy Clots?

Hello.The last 2 months i have had my period early (July 7-12)(August 6-11) I usually get my period around the 15-17 for 5-6 days. However this period (August 6-11) Is light pink, but still kind of red, and blood clots. And not as heavy as my usual period. But its still kind of heavy. What does it mean please and thank you ! P.S. my husband and i are trying to get pregnant!