I’ve been on my period for 3 weeks

Hey guys so I started on Desogestrel birth Control tablets and well I’ve been on my period for three weeks it is not as heavy as when I was off the pills yet I’m still needing sanitary products daily. For the first three months of being on the tablets it went amazing I was so happy on them. But then the past four weeks since I went to get more pills and have my checkup everything is been going wrong. Is this normal, do I have an infection and do I need to go to the doctors? Please help guys!! ❤️❤️