You are obviously trying really hard to do all the right things. Part of doing the right thing is giving everyone, including yourself, a bit of grace.
The developmental benefit of a 3rd carer in his life for 8 hours a week vastly outweighs the chicken nuggets. Having a someone who loves your child that much, makes them feel safe and cherished if you can't be there is priceless.
Meanwhile, the fact that she forgets the home made food sounds like she is not happy being told how to babysit. I'd leave it alone.
The constant interest in tv, the narrowing in tastes, these are part of coming up to 2 years old, welcome!
It will blow your mind, but all the advice is based on averages and statistics.
I have 2 boys. My eldest watched HOURS of TV. Hours. He is also very bright, sociable, and at 19 is in his final year of uni, has a job, a girlfriend, and next year is starting his masters.
My youngest wasn't interested in TV for a long time, probably not until he was 4 or 5.
The pc and ipad are now his only real connection to the outside world. He is autistic, probably has the highest iq of anyone I've ever known (and I work with physicists and doctors), and I'm grateful every day that he can learn and have a life, if 2nd hand, through the screen.
There is only one thing you're doing wrong that you absolutely have to stop now. Do NOT push yourself when it's clearly not sensible. If you have a chronic condition, it will get worse, if gradually. You have to pace yourself, let go of perfect, and give yourself and the others a big clap on the back for the amazing team you are.
I was very ill when my eldest was small, I'm not as unwell now, but I also have a chronic condition that, in my 50s, is starting to impact me daily. You need to start making peace with the idea that you probably won't be that perfect active granny, but you can be that loved and wanted granny.
Uncrease your forehead, drop your shoulders, breathe. You have what you need to make this a very happy family.