If you find this list describes you well some fair portion of the time (say, more than 20%, though even that sounds like a lot given what I know about people who don't have chronic depression), that's probably a start.
As to it being scary -- yeah, it is. One really important thing to do ahead of time if you decide to seek help is figure out how to make a safe exit if you're uncomfortable, or don't want to continue with a specific provider. Some people find that easy; others find it challenging. Not sure which you are, or how much trouble you have asserting your own boundaries, but it's a very useful skill.
One practical matter of safety here: if you want to walk away from someone and you're worried they might escalate, know that in most cases they can only act without your consent if they believe you pose some specific danger to yourself or others. Think about what you're going through that might be interpreted that way, and be careful before sharing anything like that if you think you might want to stop seeing that provider.
figure out how to make a safe exit if you're uncomfortable, or don't want to continue with a specific provider.
Yes. The first therapist I saw was so bad that I called him to cancel after the first visit (though I still didn't have the guts to say it in person). Keep in mind that this is always an option. "I don't think this is a good fit" is a totally acceptable thing to say to a therapist or doctor.
This is an extension of a comment I made that I can't find and also a request for examples. It seems plausible that, when giving advice, many people optimize for deepness or punchiness of the advice rather than for actual practical value. There may be good reasons to do this - e.g. advice that sounds deep or punchy might be more likely to be listened to - but as a corollary, there could be valuable advice that people generally don't give because it doesn't sound deep or punchy. Let's call this boring advice.
An example that's been discussed on LW several times is "make checklists." Checklists are great. We should totally make checklists. But "make checklists" is not a deep or punchy thing to say. Other examples include "google things" and "exercise."
I would like people to use this thread to post other examples of boring advice. If you can, provide evidence and/or a plausible argument that your boring advice actually is useful, but I would prefer that you err on the side of boring but not necessarily useful in the name of more thoroughly searching a plausibly under-searched part of advicespace.
Upvotes on advice posted in this thread should be based on your estimate of the usefulness of the advice; in particular, please do not vote up advice just because it sounds deep or punchy.