Normal or be worried??

My doctor put me on birth control to get me to stop bleeding and regulate my monthly. I had been bleeding for 3 months. Most of the time it was medium to light with occasional heavy bleeding. Now almost all the way through my first pack and I am bleeding VERY heavily! I’m not even to the pills that start your period. I am filling maxi pads and when I sit on the toilet I hear large splashes and the toilet will be filled with blood and large clots when I get up. Is this normal or should I be worried and call my doctor?