@patsysun you sound amazing, not everyone is willing to take on so much, I'm sure that your love and support has helped your Gran to live at home for longer than would be possible without you being there.
Sadly, dementia gets gradually worse, and as that happens it can get too hard for one person to do everything, not because you aren't trying hard enough or because you don't care, but because it just isn't possible. That's where SS support should kick in and it sounds like it has, they definitely will not be judging, they want exactly the same as you, to support your Gran to live as well and as safely as possible at home.
I would echo what takethelongwayround says, caring is hard, be kind to yourself.
See if you qualify for attendance allowance and other benefits (the Alzheimer's Society has a helpline that can help with this stuff), maybe that will help you pay for a cleaner so that you can spend more quality time with your Gran.
The Alzheimer's Society might also be able to point you in the direction of lunch clubs or activity groups that the 2 of you can go to together and meet other people so that you feel less isolated.
Ask your GP for a carers assessment, this means that someone looks at your needs and can offer help and support so that you are able to keep caring for your Gran for as long as you want to.
Your love for your Gran really shines through your OP. Please let people support you both so that you can be there for each other for as long as possible
Trust me, as a healthcare professional who looks after people with dementia, we are in awe of people like you and want to do everything we can to help.

PS do you know that you are entitled to a flu jab?