Heavy flow? Do I need a different cup?

Since having my mirena removed my flow has become very heavy compared to what I was used to before the birth of my second child. It is only very heavy for the first two to three days but during that time I am overflowing my large uk moon cup every 2-3 hours. It is constantly leaking as well during this time. I am not sure if this is just something to live with or if I could change cups and have a better result. any suggestions welcome, thank you!