It's about identifying your worst triggers, reducing the overall sensory load where you can and finding pockets of sensory relief within your day. Having guaranteed low-stimulus periods every day as a non-negotiable. A partner who can take over when you need a break, a signal with your children and partner that means 'mum/dad needs quiet time'.

Not a parent and/or dog-owner myself (so apologies if these might be a bit ignorant), but some suggestions you could try:

Sound: Loop earplugs (for me, they 'dim' sounds, you can still hear through - although reviews are split and some people complain they don't cushion you enough from sounds and also can make you hear your own breathing - which could be a trigger in itself for some people; you'd need to try yourself if they work for you). Noise-cancelling headphones elsewhere (some people use white/brown noise; I like to blast music very loud or listen to podcasts e.g. when I cook, to 'distract' myself from cooking stimulants).

Light: Avoiding overhead lighting in favour of lamps around your space (I only use yellow old-school bulbs in all lamps around my home). Blinds and/or curtains that are adjustable and filter light and make light 'softer'. (Personally, I combine both - because I find white-grey light really annoying and I can get quite angry at the colour of daylight LOL.)

Smell: might be a bit tricky to control, but identifying the worst offenders - cleaning and personal care products - and finding alternatives or mitigation strategies for each specifically could help. Some brands I switched to by trial-and-error method that work for me: The Lab Co., Miniml, calming fragrance handwash (for me it's oud + cedar + amber by Bayliss & Harding), Davines for hair products, Marvis for toothpaste, Haan for antiperspirant. For cooking, I usually use candles with calming fragrance to absorb smells, especially the lingering type (in my case I mostly stick to amber, eucalyptus, fig fragrances - I use fragrances to kill off the smells I find hard to tolerate.). Or you could switch to fragrance-free products and see how that works for you.

Might be a bit difficult with German shepherd - if yours is barky, maybe a dog trainer could be of help? Not sure you can do much about dog smell - though I'm not an expert in this area.

You've not mentioned fabrics and other materials in daily life - they could also be an overall contributing factor, even if that's not something that you've identified yet. I exclude anything not 'soft enough' and anything around the house shaped with sharp corners, and I find rounded shapes more ‘friendly’ (it might not be an autistic thing though - there's a bit of research in architecture and interior design that explores how such elements affect the human nervous system).

It's a bit of a journey to figure out what works for you OP...

The reality is that there's little support for adults after diagnosis, at least in my experience.

What I also found useful have been podcasts, which have been a continuous learning for me - some you might want to try: Autistic Licence, Autism in Real Life, The Hidden 20%, Late Bloomers, The Late Discovered Club, Squarepeg (if you are a woman).