Two of the bombs were lost with the first life. The third was used after I came back because I put myself in a box. The run was ugly in as many ways as you can imagine; the fact that it made it all the way to LFS is proof that I can win this. I hit a fairy right at the end of Nue in stage 4, again with one or two bombs in stock, thus missing the extra life. That alone could be said to have cost me the run, or any one of the other abysmal failures throughout.
If you made it there, you can definitely win, absolutely positively. In the end, how far you get depends on how many mistakes you make, every little thing can add up, but at the same time one mistake can help you relax and ease off the tension, at least that's how it is with me, which is why I find it hard to calculate the overall success of a run if I include all mistakes, since mistakes aren't necessarily a bad thing if they allow me to step up my game by becoming less tense.
Granted, I found UFO to be more than unique with LFS. I don't really know if it's just the first game where I actually noticed it, but Byakuren is terrible with all the invincibility and damage reduction she gets during her last two Spellcards. If you die, you're invincible for roughly 6-7 seconds, but during that timeframe, Byakuren also takes damage like she's covered in steel plates. Same with the 1 second of invincibility after a Bomb (though it's less noticable there).
As a result, I found that living through LFS is not guaranteed with more resources - taking other last Spellcards into consideration, I'd definitely put the way LFS works into the same category as VoWG. If you can do it, you'll live, but if you can't, no resources on earth will help you (see me getting there with two Extra Lives and still getting my ass kicked despite not dying with Bombs in stock. Granted, I did terribly there, so I kind of deserved it, but you usually expect to win if you get to the last Spellcard with so many resources).
Due to that, I always thought it was kind of tough to have so much depend on how well you can handle that one Spellcard, but that's probably the purpose of last Spellcards anyway.
Either way, keep it up, you can definitely do it!