Ive only just started wearing tampons and every time I insert one (with an applicator) it goes in all the way and I cant feel it, but then after about 30-60 minutes I can feel it slipping out and when I try to push it further up with my finger, it wont go up! and it starts leaking (the tampon isnt full yet because its only been in for about 30 minutes and my period isn't heavy) what am I doing wrong?