Kudos should be given for your methodical attempt at identification. Most people just look at pictures, only. So I think you will view the forthcoming as it is intended (a learning tool), rather than criticism (which it is not!).
All species in the family Liliaceae have parallel veins. Your plant has net veins. A good source of information for North American plants is the Flora of North America (FNA), where full descriptions are given for not only species and lower ranks, but also those above, like families. Unfortunately, the decades long FNA project is not complete in that all the families are not finished, but all that are published are complete. So one might find Liliaceae listed, but not Fabaceae, for instance. Under the family names, a full description common to all species within that family will be given. A simple dichotomous key will never show all the characteristics, only the differentiating ones.
http://www.efloras.org/flora_p...
http://floranorthamerica.org/f...
When I was 16 years old, I didn't even know what a botanical plant family was!
You're going to be a great botanist, Vivi0912.
Learn Botanical Latin; you will never regret it!
, Vivi0912!
