So sorry to welcome you here. Ask any question quickly and you'll hopefully find quick solutions as each new crisis arises. I read about how fast your other family members progressed and that is indeed quick. Staying ahead will be a sprint.
Although no riluzole sounds hard on the first read it's pretty solid advice. If it prolongs life duration, say, 10%, it's important for slow-progressors but wont' make a noticable impact in super quick progressors. You might have even had side effects that would compromise your quality of life.
I don't want to bumm you out even more but you said yourself you are a rationale person. You don't have long, think about how you want to spend your time, what's important to you, whom you want to talk to, what you want people to remember you by. With rapid progression you might not be able to find a solution for every problem quick enough. My PALS lived for 13 month after getting diagnosed. Once the insurance would come through and pay for just part of some transfer grips he lacked the strength to use grips at all. Lots of energy spent there. So choose your battles wisely. Things that will grind slow-progression PALS down over the years won't be a problem for you. It's cynic but true.
I found that (low-tech) communication is one of the most important things. Making your wishes known in every situation shouldn't be a problem. We used a very simple technique shown in a YouTube video. Search for "Jason Becker Communication - Vocal Eyes" if your interested in a good and quick system. After some time me and my boyfriend new the letter board by heart and he could move his eyes until the end and even tell me exactly what music he wanted to hear in his last hours.
Take your friends and family along for your journey. Tell them how you feel, listen to their everyday grievances. Nobody should be alone with this s##t and you'll always have support here.