It's not surprising if you are tired. Partly it's a lot of stress and worry, and also you are constantly checking on him. It's really good you have the history of nursing him, that is surely helpful in this situation!
On the urination, it's good he finally went. If he has trouble standing in the litter box, he may be holding his urine on purpose. You may be able to help him by standing him in the box and expressing his bladder. (Or you could do it outdoors if he ever goes outdoors.) You could help him initiate urination by squeezing his abdomen.
This article descibes expressing the bladder, if you are not already familiar with it. I recommend starting at the end of the article where there are a lot of videos. You will see videos demonstrating expressing a bladder for a cat. viewtopic.php?f=5&t=16027
The thing is, he really needs to be emptying his bladder every 8 hours to prevent urinary infection, or a distended, stretched out bladder, or the build up of "sludge" that can lead to stones and crystals. I would think at least every 12 hours in a short term situation. Also, if he wets his skin, that could lead to skin breakdown. If he does that again, I would just put his hindquarters under running water (like maybe the kitchen faucet or a laundry faucet if you have one?) to rinse him clean. I'm guessing you already did that because it sounds like he's not grooming yet.
You also want to watch that he does not get constipated. If he is not eliminating, I would recommend asking the vet for lactulose syrup. It is a stool softener that is not habit forming and safe for long term use. It only takes a little, and you can adjust the dose as needed. If he gets really constipated, he may need an enema at the vet's office. So anything you can do to get him eliminating before he gets constipated would be helpful.
That is cool about listening to the cars. Three is still a young kitty.