How soon you were seen wouldn’t have made any difference, I’m afraid. One of the reasons MS is a non-urgent referral is not only that it’s not immediately life-threatening, but that so little can be done. They certainly could not have prevented your relapse, even if they’d acted immediately.
DMDs do work to reduce frequency and/or severity of relapses for some people, but take weeks if not months to get up to full effectiveness, so even if you’d started them the same day (highly unlikely, as it usually takes weeks of administration, if nothing else), they wouldn’t have worked immediately to prevent a relapse that had already started, or was just about to.
Similarly with steroids. They CAN sometimes help to recover more quickly from a relapse. But studies have shown they make no difference to the amount of damage that is done, or how completely you recover - only how quickly.
So please don’t torment yourself thinking faster referral could have prevented the relapse, or reduced the amount of damage. It couldn’t.
I don’t mean to sound unkind when I say that’s just the way it is. But MS gives us enough to be sad about, without believing - wrongly - that it all could have turned differently if only we’d seen somebody sooner. There is nobody to blame for your relapse - not the GP, not yourself. Preventing relapses is the holy grail of MS research, but so far, even the best drugs we have are only moderately successful, and don’t work instantly, so sending you to hospital the same day, and shooting you full of drugs wouldn’t have meant everything would be fine now, and that you would have had no relapse, and no brain or spine lesions.
One day they might be able to test for an imminent relapse and stop it, but not at the moment. So try to accept it as an act of God, or fate, or nature, or whatever it is you believe in. Nothing humans could have stopped.
You don’t say how long ago this relapse was, but it can take many months to recover, so if it was all quite recent, there’s still plenty of chance of improvement.