Well, your first problem is you have too many arrows.

I usually worry because "Can you do something about is" is an uncertain variable where I'm not sure how much control I truly have

I'm not sure I'd agree with that generalisation.

Is that why you personally worry about something?

I mean if a meteor is coming, I'm not worrying.

Agreed but I think the implication is more "if you can do something about it, then there's nothing to worry about."

It's ultimately easy to tell apart because the things in our control have vastly different qualities from those which are not. Quoth Epictetus:

Some things are in our control and others not. Things in our control are opinion, pursuit, desire, aversion, and, in a word, whatever are our own actions. Things not in our control are body, property, reputation, command, and, in one word, whatever are not our own actions.

The things in our control are by nature free, unrestrained, unhindered; but those not in our control are weak, slavish, restrained, belonging to others. Remember, then, that if you suppose that things which are slavish by nature are also free, and that what belongs to others is your own, then you will be hindered. You will lament, you will be disturbed, and you will find fault both with gods and men. But if you suppose that only to be your own which is your own, and what belongs to others such as it really is, then no one will ever compel you or restrain you. Further, you will find fault with no one or accuse no one. You will do nothing against your will. No one will hurt you, you will have no enemies, and you not be harmed.

Aiming therefore at such great things, remember that you must not allow yourself to be carried, even with a slight tendency, towards the attainment of lesser things. Instead, you must entirely quit some things and for the present postpone the rest. But if you would both have these great things, along with power and riches, then you will not gain even the latter, because you aim at the former too: but you will absolutely fail of the former, by which alone happiness and freedom are achieved.

Work, therefore to be able to say to every harsh appearance, "You are but an appearance, and not absolutely the thing you appear to be." And then examine it by those rules which you have, and first, and chiefly, by this: whether it concerns the things which are in our own control, or those which are not; and, if it concerns anything not in our control, be prepared to say that it is nothing to you.

Now the list of things under our control might seem small -- but it's actually real control. You can't control that an arrow you shoot will hit the target, a gust of wind may take it away and you're not controlling the wind. Have the opinion (under your control) that you shall hit, and that gust of wind comes, and when you miss you'll be wretched, so don't have that opinion. But still do take that shot unless it's impossible, in which case find a possible one.

In the afterlife, first thing he'll say is 'Don't EVEN say it..."

I just wanted to say I appreciate the way you wrote this and didn't hide the fact it's taken you a lot of work, and is an ongoing practice. I see these types of things get suggested far too often without that context. "Just meditate" really takes away from how much discipline over years or a lifetime it takes. There's nothing easy or quick about it, and it takes a lot of courage to keep it up.

You worry about uncertainty. There is no uncertainty in this flow chart. Worrying about things that are defined and known is not healthy, but that's not to say that stable people never worry about things they know the solution to or never worry even though there aren't any real problems. The distinction really is if you're able to make yourself stop worry or not, in a healthy way, or if worry consumes you to the point of anxiety.

It can be difficult. My partner has anxiety all the time and it is hard to impart the sense of security and stability that I have to her.

I guess the thing missing from the chart is "can you do something about it?" -> "do something" -> "don't worry." Worry is only useful in that it prompts us to go "this thing could be a problem" and take action to address it. If we can't do anything about it (or aren't deciding to do something) then devoting energy and thought cycles to worrying doesn't benefit us.

I mean, that's how my ADHD and anxiety combo works: every waking moment is either

A: really thinking about everything, including completely inconsequential stuff, my brain making me super worried about most of it

Or

B: trying with various degrees of success to distract myself away from doing A. This in turn often tends to make me forget things that I DO need to be aware of, such as appointments etc, worsening A.

It's so fucking exhausting tbh 😮‍💨

Same here. I actually just decided last night that I hate who I am so much that I'm going to "kill myself" in that I'm going to try to completely kill off the person that I "was."

I have a lot of respect for transgender people who sort of go through a similar thing so I'm taking inspiration from them and saying old asafum is dead, I killed him, and in his place I'll be a new asafum.