First time bleaching. Help!

Hey everyone! Thanks in advance for reading: this MIGHT belong in "horror stories"--I'm not sure yet. It depends on how this goes.

So I've been salon-bleaching/dyeing my hair for about three years, but a few months ago I started doing my own dyeing with semi-permanents between salon visits in order to touch up the colour. It was super easy, and my salon was easily 45 minutes away from where I lived, so I figured I would try doing my own lightening as well. I spoke to a few friends and then went into Sally Beauty to ask them for advice. At this point I already had dyed bluish hair, so my plan was to both hit up my roots and go for my hair as well so I could try and do an ashy blonde/pure gray. My natural hair colour is a dark brown with a lot of red undertones.

The combined advice I got from friends/SB was, I think... not great. I was told a toner was optional, so I didn't bother with toner, figuring I was taking it slow. Last weekend, I hit my hair with ion 10 volume developer, going for both the roots and the preexisting blue dye. It stripped the dye away perfectly leaving me with a platinum blond along the shaft, but my virgin roots had only gone bright orange. So I deep conditioned, slept on it, and did another hit on the roots the next day. That got my roots down enough that I decided to go for it and try applying a gray (Ion Brights semi-permanent Titanium)

The end result was... okay. My roots were clearly defined from the salon-bleached part of my hair and there was a lot of brassiness underneath. So I went back to SB and they advised that after I wait a week I try again, this time with a 20 developer and red gold colour corrector. So I did THAT... but it turned out that "Titanium" has some pink undertones, and those were left behind.

I don't mind pink. Kinda... Tonksy. But I was trying to go for gray. So I went BACK to SB today. My hair was doing fine despite being bleached twice a week ago, but I definitely didn't want to hit it with bleach again if I didn't have to--I was thinking I'd give up on gray, go for a nice brown colour, and just let my hair grow out (I wear it very short, so it wouldn't take more than a few months to reboot and start from scratch).

THIS time, the shop assistant informed me I'd gone about it all wrong: she advised that I bleach again with a color remover, and then follow up with a toner, and then from that point I'd be color corrected to go with whichever dye I wanted. And she recommended a permanent dye. I was a little worried that my hair wouldn't survive both a bleaching AND toner AND permanent (using 20 volume each time), but she reassured me that it should be okay.

So that brings me to where I'm at now: I used the color remover first and it did an okay job. There are still a few strands of pinkish hair in there, but whatever--at this point, I'll deal with a couple pink undertones. But my hair's feeling pretty brittle, and I'm anxious about hitting it with another round of 20 volume even for one thing (toner or dye), let alone both. I have it in a hair mask right now.

And the final problem: Sally Beauty is kinda far away from my house, and at this point it's hard to feel excited about going back out there when I feel like I've gotten a collection of ill-fitting advice. I have a box of semi-permanent "Storm" in the house but I'm worried that without a toner I'll still just have to deal with weird brassy roots (even though yesterday's hit included red gold color corrector) and I'll be back where I 'started'. Should I just go to Walmart and pick up a box of semi-permanent dark brown dye and let this all ride out?

Extra complications: I'm going camping in a couple days, and when I get back I'm immediately scheduled for a breast reduction, which means no lifting my arms above my head for eight weeks. So if I let it rest for a week I'm committing to having bleached hair vibe for two months (or going back to a salon, which I won't feel like doing when I'm recovering from surgery)

Any advice or guidance would be appreciated--at this point, I've given up on silver/gray hair and just wanna do something manageable.

tl;dr: bleached hair for the first time after getting a lot of conflicting advice, now I'm worried my hair's too brittle to see it through. Will drugstore-brand brown settle me back down to a manageable state while I rehabilitate or do I need to cut my losses (and, I dunno, shave my head)

Thanks so much for any advice or guidance you could give to this overwhelming newbie!!