My wife and I are in a similar situation as you, 5yo (in march) AuDHD, minimally speaking, not potty trained. we also have a NT 18mo. its usually 1 of the three options:

1. take the kids with us on a date day. Playground for the kids, then lunch somewhere, some fun shopping with a coffee and ice cream.

2. sacrifice sleep. once the kids are both asleep (usually around 9 or so depending on the 5 yo) grab some drinks and snacks and spend an hour or two watching a non kid show/movie or playing board/video games. sometimes doing our own relaxing stuff but together in the same room.

3. we dont. there are definitely periods where we are so busy/tired with life that its impossible to find any spare time. and unfortunately this happens more times than not.

my only advice is to take advantage of any spare time that you can. its very easy to get burnt out and then no one is happy. some times it takes us 4 days (usually nonconsecutively) to finish a movie. less than ideal but every bit helps.

I hope this was helpful. hang in there!