@Ellie K - Some good advice has already been posted! I have a few extra tips that I hope are helpful. (perhaps too late for the meeting but still helpful later?)
I may be repeating a couple things already mentioned -- sorry about that! But it's easier to think through things as a whole rather than leave out the bits mentioned above.
So, here are a few things to keep in mind. I hope I've got all the details straight. This is based on my own experience so things may have changed. Also, I may have confused details that I thought were general but were merely based on my own workplace policies.
As mentioned above, look through the options you have with your short term disability insurance before you consider applying for long term disability (LTD).
Short term disability:
These insurance benefits are usually (always?) paid for by the employee, deducted from the paycheck. The period for short term disability varies. At my workplace it was one year (that seemed pretty long, actually). Some places may have either shorter or longer periods.
Because short term disability is paid for by the employee it is not considered an employee benefit. That means it does not fall under ERISA disability laws. So it's usually much easier to qualify for short term disability benefits.
If you feel you are able to work part time then you may be able to go on some sort of part time or partial medical leave. That means part of your benefits are paid for by short term disability insurance while the hours that you work are considered salary. This is what I did, several times, before I finally got too sick to work at all and had to apply for LTD benefits. Some of my short term disability periods were a full medical leave (no working at all) while others were working part time hours (e.g., 20 hours per week).
It's important to note that if you choose to go on part time hours now *without it being part of a disablity leave*, and then later you apply for LTD benefits, your LTD benefits will probably be based on your part time salary/earnings and not on your full time salary. And I think the same thing will happen to your social security SSDI benefits since they are based on the taxes collected. This means a much larger reduction in your SSDI and LTD benefits.
In short, I would advise folks not to change to a part time schedule unless they have no other choice. Part time schedules are seen as a choice that the employee wants to work less. Disability is meant for folks who are too sick to work. These are two different things.
Long term disability (LTD):
LTD that is provided by an employer is usually (some exceptions) covered by ERISA law. This makes it very difficult to get benefits. Too long to cover here. Just trust me on this.
If you decided to apply for LTD then make sure you see a lawyer first. Don't wait until after you have been denied. That approach is fine for SSDI disability but there are all sorts of procedural reasons why that is wrong for ERISA LTD claims. Even if you just pay for an hour or two of a lawyer's time before applying it will probably be worth it.
And make sure you get a copy of the LTD policy. One thing to note is that LTD coverage can be very different depending on the company.
For example, the idea that mental illness is covered for 2 years did not apply to my company's LTD policy. There was ZERO coverage for mental illness (and not just depression was excluded, any mental illness, no matter how serious, was excluded completely). This did not apply to me but I bring it up just so people are aware of how different these policies can be.
I also hope that with rest and treatment you won't have to apply for LTD. At the very least I hope you will be able to put it off for some years. But there are people who go into remission with early rest and treatment. I hope you are one of those!
Wishing you all the best!!!