Please help. My period is weird this month

Went to the doctor last month because of my thin short period. She did test to realize I’m not pregnant. My hormones were check and It came back normal. So this month, I witness spotting of brownish blood. I thought my period was starting that date but nope it didn’t. I check my menstruation calendar and realize my period came at the beginning and end of August. So since it came 2 in August, does that mean that was the period for SePtember? I’m starting to get worried. Please help!