Why can’t I ever fill up a tampon? It always leaks

For the past like 6 months my period blood has become mostly small clots and what isn’t clotted is very mucus-y. I always use the same tampons but since it started getting all clotted it always just soaks one side of the tampon then starts to leak and the rest of it is unused. I use the U by Kotex tampons. Also I don’t have anymore pain than usual or anything. My period is always 6 days, the first 2 days I get bad back pain and medium/heavy bleeding, then the other 4 I have pretty much no symptoms and it’s really light. Is something wrong with my period or is that normal? Do I just need to try a different kind of tampon? I’ve tried a few different kinds before the clotting issue and didn’t like them as much