Boy, times have changed!
I am glad you are happy about it. I was not so thrilled. I think I was 13 as well and much later than all my friends but that was OK with me. It really cramped my style, pardon the pun! LOL
Just take care of yourself and like was said, drink lots of water, it will help your complexion and your period.
As far as the tampons go, be wise. My daughter had a friend get Toxic Shock Syndrome. We were all shocked as it seemed like something they put warnings on the label for but it really never happended to anyone. She was one sick young lady and still has troubles from it 6 years later. It is a very serious illness and needs to be taken seriously.
What happens is each time you remove one it takes a few skin cells with it and opens up the wall to bacteria. The trick is to not use too absorbant of a tampon, Use the lightest one you can get away with as when you remove them and they are dry they remove more skin cells. For example do not use the super absorbant if you dont need them. If you want to use them start with the lightest absorbancy and see how it goes and move up till you find the one that will last you a few hours. This girls doctor also suggested never wearing one at night and wearing pads then, a practice my daughter started and still does.
This gal was very very sick and in ICU for 3 weeks, and in the hospital for 6 weeks total. She missed the last 3 months of her senior year from it, it was very touch and go and some of her organs are permanently damaged, cant remember which ones they were now.
Sorry, dont want to scare you but I think we all are a little lazy about such things until tragedy reminds us.