Hiya, I Am On The 21 Day Pill And Started

Hiya, I am on the 21 day pill and started my period break, after three days I began my period which was really heavy. I ended the break early because I had a dance show and didn't want to be on my period, however im on day three of my new pack of pills and I am still bleeding really heavily? what is going on? I am taking the microgynon 30 pill if that helps.
I also am worrying because after reading online it says to start the new pill the day you started your first pack but I did not do this, does that make a difference? PLEASE HELP!!!
I am 17 years old btw