Tampons.....ugh!! Help please!!!!?

So.... I've had my period for about a year and have always wanted to use them. I've been trying for SO long and even got the littlest kind with a plastic applicator and everything. I've been trying the relax, try pointing it towards the small of your back, put one foot on the toilet seat. But it WON'T go in, it goes in about half way or a little less, then it just stops. What can I do to make this work? I HAVE to be able to put one in next month because I'm going on a cruise so.... yeah. And I can't ask my mom for help because I already tried that. PLEASE please help me :(