Help with internet problems?

Me and my family are all connected to the same internet connection and everyone else has a great stable connection, but for some reason my connection is always low and unstable. Everyone else has 54 Mbs while my connection shifts from 11 Mbs to 54 Mbs never staying in one place. My connection also randomly disconnects sometimes. Since I share my internet with my family it should be the same, but it isn't. Can anyone help me?