Just casually browsing around here, and while I have no advice in terms of nitty gritty nuts and bolts of making this costume, I see your frustrations, and I just want to offer my encouragement toward patience in the process.
My own story goes (if you're so interested in hearing it and have the patience to read through all this), I originally got interested in joining in the RL in 2012. After a bit, I finally decided what costume I wanted to do: the Bespin Leia (now officially renamed Cloud City Leia). But go me, I went and picked one that was going to involve a ton of embroidery! And my sewing skills were suuuuuuuuper basic. Like, I can hand-sew a button on something, or sew ribbons on my pointe shoes, and that's about as skilled as I was. And my knowledge of fabric types, or what was needed/good for the costume was basically zilch. So I definitely needed a ton of help.
I saved up so I could buy materials and pay for some skilled help, and asked around and asked around, and finally found someone to help me. Unfortunately, she wasn't familiar with the requirements, and I didn't know enough of what I was doing, and we ended up making some fabric purchases that were just all wrong, and couldn't really be repurposed and made to look right. But before I realized they were wrong, the person I found to help me had to back out. Eventually, I found someone else to help, and we got it sewn up. Meanwhile, I had discovered the mom of a friend of mine owned an embroidery machine, who basically offered to let me use it, if I could learn how, and were willing to do the work. By this time, I'd worn the unembroidered version of the costume to Star Wars Celebration 2015, in Anaheim (met Carrie Fisher in it!), and it was about that same time that I was realizing how wrong my fabrics were - after it was all sewn of course (... Carrie might have remarked on hers looking a little different, too... aaahhhh).
If you've been noting my dates here, you'll see that three years had passed at that time. And it having taken me three years to reach that point, I was definitely not loving the idea of basically starting from scratch. But, finally, I bit the bullet and did so. Saved up some more, so that I could.
In 2017 (yup, two years later!) I was attending SWC in Orlando, and happened to encounter someone wearing a Cloud City Leia costume - where the pattern that I had thought I was going to have to embroider was instead printed on it! AND she was hopeful of becoming an approved member of RL with it! (I later confirmed that she was indeed approved.) This was a game-changer for me. She shared with me where she bought her fabrics, too. A huge help!
By this time, I'd finally learned, oh, I should be getting help from the forums. I ordered some samples of the fabric that I'd received advice for. I showed the samples in a thread on the RL forums, and they confirmed they thought it should work. So I ordered the fabric. It was not cheap, by any means. But I didn't want to repeat my mistakes of getting fabric that wasn't going to work, and if that meant it took me longer to save up so I could get the right stuff, and do it right, so be it.
Unfortunately, by the time it came time to sewing it (2018? 2019?), the person who had sewn up my last costume was no longer able to do so. But fortunately, someone I met while spotting at a RL/501st event, someone who is in the same general part of the state as me, was able to make a recommendation for a seamstress in a shop, who had helped with a Vader build. We really took our time with it (partly because I allowed her to prioritize other customers since I didn't have a hard deadline for an event I knew I wanted it for, and partly so we could take our time making sure we got all the details right, checking in on the forums along the way, and partly because oh hey, we're in the midst of a pandemic and things are weird, and the event I DID think I was going to want it for got pushed back two years). But eventually, it did get done. And I finally get the rest of the bits and pieces taken care of - the shoes and the hair (though I admit, I had a few qualms about whether or not they'd be approved).
And then, in May of this year - 2022 - yes, 10 years after I first decided I was interested - I was approved. Finally.
So my point is a couple of things.
One, the advice to take a little bit of extra time to make sure you're doing it right? So solid advice. Because I didn't, it took me longer. And I spent a pretty penny more than I originally had planned for. Doing it fast but wrong will cause more frustrations than taking an extra minute to do it right the first time. (It also took me longer because I didn't push as fast as I could have, but it still would have taken a while, and also, that's beside the point, because I can definitely see you don't have my same issue there!)
Two, the Legions aren't going to disappear. They'll still be here as soon as you're approved, no matter how long that might take. Ready to welcome you with your new costume. And you will be offered plenty of opportunities to troop. Before you know it, I'm willing to bet that these troubles will be so far in your rearview mirror, you'll hardly think of them as you do troop after troop. Or that if you do think of them, it can heighten your appreciation for the hard work it took you to get to where you are now, every time you put on your costume. Either way.
Finally: As you work toward your goal, one final thing:
May the Force Be With You!