Which iud should I get?

So I’ve been doing my research looking at different types of iud’s and I’m still kind of confused on which one to go with. Ever since I started my period when I was 15 they have been horrible for me like incredibly sick and painful. I’m on the pill and have been for a couple years now. They’ve tried fluctuating it and when they tried to give me a higher dose it made me incredibly emotional and still didn’t help lighten up my periods so I’m still struggling with bad heavy periods and pain. Which iud would be best for potentially lightening up my periods? I’m 20 now and haven’t had any kids.