Tampon Issues (Long Post, Sorrry)

So Ive been having my period for years but until recently I've never been able to wear tampons. Like my body would just reject them or maybe I wasnt putting them in properly I'm not sure. But now I use them but I still HAVE to wear a pad or a pantyliner because I get small amounts of blood on my underwear. Am I maybe not pushing it in far enough/pushing it in too far? Or should I switch to a different brand because im using U by kotex so Im just confused becauss I'd rather be able to just wear tampons without anything else.