I think statistics on height are just that: averages. The problem with the internet is the info scares the pants off us - but really, what are you going to do about it? I think the less everyone freaks out about this, the better. Based on the height of your and your husband, she's not going to be huge anyway, but you really can't tell at this young age what's in store for her.
I'd show her both tampons and pads, and see how she feels about it. A good book or two for reference would be excellent - leave them in her room so she can leaf through them whenever she wants. Years ago, girls started on pads because no one wanted to teach them too much about their bodies and vaginas, let alone have them touching themselves or looking at themselves in the mirror. So offer her choices, and support her as I am sure you will. I'd have some of each in the house. Let her know that pads can provide extra security at night especially if her flow changes over time. Let her know that this period might not be the same as the next one (which might not be next month either).
When I worked in a women's clinic, we had to do a lot of supportive coaching to teach women how to insert a new diaphragm, and these were women who supposedly had had some health education. They were often afraid things would get "lost" inside so we had to do a lot of re-education. Make sure whatever books you give her address these myths. You don't want her on the internet researching things herself! So however she wants you to support her learning to use a tampon, you'll do it - just offer her options (watching her, standing outside the door, or leaving her on her own even if she has to "waste" a tampon or two while she practices.
Of course, make sure she knows how to dispose of tampons and pads properly (if you have other kids or if you have dogs, you want to protect waste products from them!). A step-on trash can with a liner might be good. And make sure she changes relatively frequently. A lot of girls in swimsuits and leotards need to be reminded how to tuck the tampon string up inside so it doesn't show or get caught in the elastic.
Good luck!