Heavy bleeding then real light bleeding 🤷🏾‍♀️

So I started my period the 10th of this month.. had heavy bleeding for about a day in a half. Then the heavy bleeding randomly stopped and turned into light bleeding, light pink and there was some brown as well. My periods are usually about 3-4 days long. Yes I know that bleeding becomes lighter as your period is coming to an end, but the heavy bleeding stopped earlier than normal. I’m so confused. This hasn’t just happened before as far as I remember. Could this be an early sign of pregnancy? Or could it be something very more serious? Me and my boyfriend have been ttc for about a year now.