Most of falling gently, is learning to relax when you fall, and getting practice at falling. Practice is needed because that helps you speed up your reflexes.
It has been estimated that trained simple reflexes take about .1 seconds, but trained reflexes with a decision (such as whether to try to prevent the fall, and how) take about .3 seconds, though of course that varies. But if you haven't trained yourself, it may seem like you don't have enough time to figure out what to do.
From adult standing height, a fall takes about .7 to .8 seconds. But in a spiral, you are somewhat less than standing height. A rough formula is that in s seconds, you fall about 4.9 * s * s meters, which is about 16 * s * s feet.
That means there is more than enough time to do it right.
But there are other factors. E.g., If you are moving forward fast , and you catch a toepick, that can cause your body to rotate into the fall faster.
But for the most part you can still learn to do it gently.
I suggest you start practicing from a sitting position, advance to a kneeling position, then a bent knee standing position, then a full standing position. Practice falls in all directions.
It is much easier on you to take your initial impact on soft tissue than hard bone. And if your muscles tense, you become much more fragile.
Some of the same principles apply to collisions - with a wall, with other skaters. And to other athletic things that can cause injury.
While you are still learning to fall right, don't be too embarrassed to wear a helmet and other hockey or inline skating protective equipment, like wrist guards, knee pads, rear end padding... Some meanies might laugh at you - but I point out that hockey players, who are supposed to be "tough", often wear helmets & padding too. BTW, some helmets, including hockey helmets, ski helmets, and whitewater boating helmets, and some others, can be strapped on. And some helmets, like most bicycle (and maybe construction helmets?) helmets, aren't designed to take more than one fall or collision (the others I just named can probably take many falls or collisions). I guess you could make yourself foam pads for everything but your head by cutting a camping foam pad, that might cost $15, or other pieces of reasonably soft foam, and slip it under clothing.
I will send you a link to my web page on falling gently, but I admit it is pretty long. I became something of a fanatic about learning to fall. The rules of this forum don't let me post the link publically here.