I Had A Myomectomy In September With Ten Fibroids Removed,

I had a myomectomy in september with ten fibroids removed, measuring fr 3 cm to 7.5 cm. Prior to that had a gnrh jab to suspend periods. Got my first period yesterday since the last in apr last year.
I notice that day 2 today, its rather heavy. I have used four pads already, and its just half the day, from midnight till noon. What could be wrong.