Me and dh work full time, one dd, one ds on the way, and have no relatives around to help us.
We've been there: chaos, stress, no time. But we've come out the other side by simplifying everything:
2 week meal rota like pps suggested with an online shop set up with the ingredients
A massive clear out of stuff. Stuff needs tidying and cleaning. Less stuff means less tidying and cleaning so whatever we didn't absolutely need we got rid of.
Dropping our standards and not letting cleaning stress us, plus cleaner once a week.
Just getting up in the morning and getting out. No nonsense, out the door with a premade lunch and to the playground where dd can be as messy as she wants, tiring herself out in the process.
Get an early bedtime and wake up early in the morning. Things are so much easier to handle during day light. If you can, find time for a walk every day to reset when you are feeling stressed.
Any sources of stress just say no. Family members burdening you - just say no. If you were wiped out tomorrow they would find a way. Friends more hassle than they are worth? Don't answer the phone.
Once you have a bit more space in your life you can start investing in improvements for the long term. Untidy cables, get a cable holder. Too many meals to cook? Batch cook. Over buy on underwear and socks so if the washing piles up, who cares, just blast it once a fortnight. Rethink what dirty clothes really means. Smelly = dirty. Dropped ketchup on your tshirt but not going anywhere, just wear it nobody cares or will even see you.
And never say yes to new, stressful projects or tasks. Just say no. Keep it simple and cut out all the unnecessary things you don't need.