Hey chryanna, you sound like you have your head screwed on tight, I don't think you are even a little bit insane, you should just go ahead and do it!
RE: directions, there is not really a Transamerica Trail "in real life" - meaning, it's generally not marked on road signs. I hear there are a few places where there are some signs, but you do need a map. You need paper maps or a gps (I recommend paper maps see below, plus regular state road maps for an overview). A GPS enabled cell phone is only going to work where there is cell service, which mostly you probably won't have when you are lost. And map reading is a skill, which can be improved with practice - you'll get better at it.
Here's where to get the official map:
www.adventurecycling.org
become a member for a map discount and to support a great organization. This map has locations of services (camping, food, bike shops), turn by turn directions, elevation profiles, a few points of interest. It's very useful.
Also, you could post a companions-wanted ad on Adventure Cycling's web site, but it doesn't really sound like you want one, which is just fine. I hear it's pretty common on the TA to encounter other riders and ride for a few hours or days or weeks with them, if you find yourselves compatible. I did have this happen to me a few times on other Adv.Cycl. routes. (I haven't done the TA)
RE: camping and riding alone - I'm a (much older) small woman, and have done a bunch of this stuff solo. It's fine, just be aware of your surroundings, and if something "feels wrong" it probably is, so take action. Just be smart - don't tell people where you are going to be staying if they are even a little creepy, introduce yourself to the camp host if there is one, and they'll look out for you, don't camp in town parks if the town seems poverty stricken or you get panhandled, that sort of thing. It's useful to have enough extra money to be able to take a motel room if things are seeming funky.
You can read a lot of touring journals, which often include packing lists, on
www.crazyguyonabike.com. You can search here if you have specific questions, and if you can't fiind the answer, post a question.
Hope you have a wonderful tour!