This may be long but I'll try to keep it as short as possible!
My Nan is in her eighties and has advanced cancer. Her overall health is very poor now - she really struggles to walk around her flat (which is small). It takes her nearly 10 minutes to walk from bedroom to kitchen and it really isn't far. She finds dressing difficult although she is mainly in bed now. She is very unsteady on her feet and has severe pain. She uses a stick to help her walk inside but outside the flat, she needs a wheelchair as she literally can't manage to walk a few meters.
If she walks to her kitchen, she struggles to carry anything such as drinks back to her bedroom because she is unsteady and has poor grip due to lymphedema (sp?). She would struggle to cook things but tbh eats very little now anyway.
She has a partner who she has been with for sometime, although he keeps his own flat he stays most nights and helps to care for her. He has had a fall though and is now in hospital awaiting an operation to pin and plate his ankle and will then be in plaster for 6-8 weeks so obviously won't be able to do anything. He is planning to stay at my Nan's when discharged due to her having no stairs.
So, the issue now is caring for my Nan (and her partner as well once he is discharged).
I do (and have always) as much as I can to help them with shopping, picking up prescriptions, taking them to appointments during my holidays (I'm a full time teacher so holidays is the only time I can do appointments). I helped them to organise a wheelchair for Nan and over the last few days I have picked up her pension/paid bills and collected the morphine prescription she needs. I have visited her and made drinks/snacks and left things where she can get them. I also took her partner some things he needed to hospital. She mentioned today that some cleaning would need doing and I said I could help but not until weekend which she was happy with.
I have an Aunt who also helps as much as she can but she has MS and can't drive, so is limited through no fault of her own.
My parents and sister have fallen out with Nan and her partner due to her partner drinking very heavily at times which is not helpful for either of them (he was drunk when he fell this time). As a result they aren't doing any helping. They have always said they'd help Nan but not her partner. However, even now he isn't there, no help is forthcoming despite my hinting.
There is no-one else to help. Nan's partner has no family.
Various people (family and professionals) have suggested carers/cleaners/shopping delivery but both Nan and her partner absolutely refuse outside help, insisting they manage between them and family.
The problem is I don't know how I'm going to cope with limited help from my Aunt and no help from anyone else to support my Nan (and eventually her partner) fully for the next two months and possibly beyond.
I love my Nan dearly and will do as much as I can but with a full time teaching job and a toddler and home of my own, I am very stretched 
I don't think carers can be 'forced' on them if they refuse. Any suggestions made by occupational therapy (or anyone else) are refused. My own little boy was ill last week (had to go to hospital although thankfully didn't stay over) so obviously I was looking after him too.
I know people deal with a lot more and I don't mean to moan but I honestly would welcome any suggestions as to how to cope with this.