if you need time out from working then taking a few months or even a couple of years now may mean you get well again quicker where continuing to push yourself now will definitely result in you becoming more ill and needing even more time off later only it may not be your choice by that time. living off benefits is difficult, you can't have all the luxuries you could whilst working, but with careful budgeting and sensible shopping you will get by.

What your mum chooses to pay for is her choice, ok it may be inconvenient to have to give up your phone, but there are ways around it...email, pay as you go etc. I guess as you are old enough to work you are old enough to get your own insurance, though if you get a medicard then won't that cover the major things? I am not in America but here once you are on sickness benefits you automatically qualify for free meds and basic councelling though there is often a looooooong wait for this.

rather than paying an attornee to help sort out your ssi have a look for a charity or advocate, we have peer advocates here which are people who have been there and got the picture/postcard who use their experience to help others free of charge or for a very low cost.