I have all kinds of advice if you want it.
I will second what someone else said: my wife and I attempted a thru of the AT after we FIREd and we made it only halfway due to injury. Don't trust any statistics you hear in drop out rates. If you look into it, there's almost no real way to know how many people drop out before Mountain Crossing, before Hot Springs, before Harper's Ferry, and so on. There are probably better stats for how many finish, but even then I wonder how accurate those stats are. But you've been thinking about this for ten years, and you have some backpacking experience, so there's only one way to scratch this itch and that's to give it a go. Even though we didn't finish, we did enjoy the experience and went on to walk the Camino Frances in Spain this past autumn.
But you should have a plan B in case you do need or want to drop out. You can keep your current housing situation, downsize to a minimal apartment, or just go homeless (or vanlife) for a while. There are upsides and downsides to both. If you continue to rent, you will have to continue paying rent for up to 7 months without using the apartment. But you'll have a home to return to and an uninterrupted rental history, which is a good thing. Also 6 months goes by pretty fast, even though it won't seem like it. If you go homeless, you'll either get rid of all your stuff or store it somewhere. If you can store somewhere for free, then great. If you would have to rent a storage unit, you'll have to do the math on whether that's cheaper than just buying all new stuff when you return (for us it was way cheaper to rent storage than to rebuy everything -- you might be surprised how much it costs to furnish your lifestyle).
Another consideration is your address. To maintain a driver's license, car registration, health insurance you need a home address. I used a friend's address for this purpose. You might be able to use your parents' address. Maintaining a tenancy makes this easy. But you will still need to have someone checking your mail. Our car registration notice is mailed every year in August, right when we were traveling. Depending on your state, you might be able to use a mailbox service, all the better if they will scan and/or forward your mail to you. But my state wouldn't let me use a mail service as my address for driver's license (although it worked for buying health insurance).
As for health insurance, look into how good it will be in the 13 states that you will walk through. Just to know if nothing else. I found that in Tennessee, I was unable to use urgent care for a minor issue and instead had to visit the ER. It was the craziest thing, due to some bizarre TN state law. I had to pay a lot for that ER visit since I have a HDHP. And it turns out I didn't have giardia, just a bad stomach virus.
I'm sure I could go on. But I'll finish with a suggestion to hike either SOBO or flip flop. The NOBO crowd is insanely busy. Even as far north as Virginia, we once we're unable to find somewhere to pitch our tent near a shelter and had to press on quite late in the day.
Have fun!