Long story.

My misery began about three years ago when my natural, ashy blonde hair developed a horrible green tint in the sunlight. Since then, I've been making a point out of not ever letting my natural hair color grow, this meaning that I'd dye it ever month or two. Different colors, yes, but none out of a two-shade range of eachother.

A little more than a year ago was the start of my experimental phase (which I'm still in), and my poor hair took a nose dive in to destruction-- though my major color would stick to a reddish zone, my bangs/front half would frequently undergo makeovers, all of which had built-in bleach.

Eventually I decided to dye the entirety black and kept the front blue, and I experienced the god awful stretchy hair of death. After getting bored with the black, I tried to dye over it with more red (while not achieving squat), then I bleached a skunk stripe down the middle, then I dyed it all brown, then darker, then red, then plum, etc. Please note that the aforementioned blue never, ever completely faded away.

Now that I've cleared up the history of my hair, I was hoping I'd be able to have some help. Yes, I keep it relatively short and my hair itself isn't a corpse anymore but I'm worried about my scalp.
My most recent color was a faded, natural dark red. I bleached it on a whim a few weeks ago and had to walk around looking like a rotten tangerine for a day before I was able to correct my mistakes with a l'oreal creme color; super light ash blonde. I now remind myself of Pikachu.

I'm not sure how I'll be able to achieve the color I want, especially with the realization that I'm losing a frightening amount of hair. It's not stretchy and it feels alright to the touch (or as alright as bleached hair could feel), but I have a mind numbing fear that one day my entire scalp is going to cling on to my comb and peel off.

I have unnervingly sensitive skin, I don't know what the hell I'm going to do. Will my fears live up to themselves and leave me bald? Should I stop being paranoid? Do I have to lighten/strip/tone my hair in order to achieve the color I'd like, and how can I do it?

Leave off the bleach. Sounds like you burned yourself. It will heal in time if you be kind to your scalp and don't throw any more harsh chemicals on it. Be careful when combing (I wouldn't be brushing as this point...) so as to not irritate the skin anymore.

To get the color you want you should probably tone your hair - not dye it.

I'd reccomend doing this after your scalp is healed a bit.
Also: Condition like crazy, lay off the blow dryer if you use it a lot and straightening will probably cause breakage right now.

And...that's all the advice I can think of. Hope it helps.

Sounds like your hair is over-processed and needs a break.
I'd wait a bit before dying your hair again especially since you'd like to use a permanent one.
Your hair may not be stretchy anymore but it sounds like it's probably breaking off.
I know because I've damaged my hair to the point where it was practically breaking off at the roots.
The hair closest to your scalp tends to be the strongest so there's a good chance you won't go bald.
But it's possible that most of it will snap off.
Treat your hair to some deep conditioning, something cheap like Aussie 3 Minute Miracle will do the trick.
Put a shower cap on and leave it on for 15-20 minutes.
When you feel like your hair is in better condition, go ahead with the blonde dye.
But make sure you do a strand test first just to be on the safe side.

bah, thank you. bah, thank you.

I can personally atest to the wonders of Aussie 3 Minute Miracle. Haha, my hair is so fried I have to deep condition almost every time I wash my hair just to convince it not to commit suicide and leap from my head.