I think a good majority of us felt at one point what you have expressed in words--How the hell did I get myself into this?
I was no top notch student in A school or Power School (3.14) with 30 - 4's to do. When I got to Charleston for Prototype, I absolutely HATED it--seriously. However, even though I didn't like it, I stuck it out because, really when you think about it, who the hell else can say they did what you did 6 years from now. There really aren't that many nukes out there.
I wanted to goto film school, to be quite honest. Instead, I found myself in the Navy nuke program because of the bonuses and advancement in rate, and getting the hell out of the Midwest. You have to remember something, that the fleet is VERY different than school. School is just a way to weed out those you don't want sitting at the power plant (and even some that sneak through are kinda scary). It's like advanced bootcamp on crack.
But when you're through, it does get better. If you're having this rough of time, don't volunteer for subs, because the culture for new guys can be tough on the mental state for the first few months. It's kinda like Lord of the Flies on speed, except its adults and not children acting manic at times.
It's pretty simple. Finish the six and get out. Don't even consider reenlisting. But after you qualify all required watchstations on your ship, start taking NPACE classes, or whatever is available. Take the GI BILL and the extra kickers they have. When you're 6 years is up, you'll have a good trade background to fall back on, you'll be wiser and more experienced than most people you know that are your age, you'll be far more passionate about what you want to do after the military, and you'll hopefully, enjoy life much better because you'll have a deeper appreciation for the things you've worked hard for.
Trust me, the nuke program definitely has it's benefits. If you purposefully fail, it could be the worst mistake you ever make. All the cones on my ship had to stand hours and hours of topside watch in Bahrain in August when it's 120F out--no nukes were doing that. As a nuke, you have a better chance of being picked up for an officer program. We had a guy on my ship that was an E-6 (10 years), he had finished his B.S. on his own, then decided he wanted to fly. He got picked up for OCS, left a few months later, then went to flight school in Pensacola.
When you are finished with the Navy, the Nuke program experience will open more doors than any other enlisted program in the military.
I run a student organization at my school that I founded for veterans, and the VP just so happens to be a nuke to. She was on a carrier, but got out before I did, and she's in the Optometry doctoral program, doing exactly what she wants to do. Me... have all my film gear, and have been doing small film production for the last year or so, and I'm starting to expand my business on the side - doing what I love to do, and not missing standing port and stbd watches as AEA or SRO!!!!
Good luck and hang in there,