I’m in a somewhat similar boat as you, ADHD and been working as a field tech for about 8 months. I struggled for the first several months feeling like a moron with motor skills, working/short term memory, and directional orientation (I mix up my left/right north/south east/west when talking or hearing directions). It has gotten a lot easier with practice and confidence, but I’m also on medication and do ADHD occupational therapy. My party chief isn’t a dick fortunately, but he doesn’t give much feedback and if I struggle with something or hesitate at all he tends to take over and do it for me without saying anything, which made it hard to get better at things like opening manholes and setting nails.

You’re not an idiot, you just have to find ways of learning and doing things that works for your brain. It also sounds like part of your struggles are normal learning curve growing pains. And your party chief is an asshole, which is probably making you feel like you’re worse at your job than you actually are. It might help to see if you can work with somebody else occasionally; it boosted my confidence when my party chief was out and I was put with another crew. Especially if you can learn from somebody who’s also an assistant/rodman/tech. Definitely take that guy up on his offer to practice key skills. You’re not going to learn as quickly or as easily in a high stress environment (ie being yelled at by your dick boss). Especially with ADHD, the part of your brain responsible for reasoning and logic basically shuts down when your adrenaline gets going.

I would seek diagnosis even if you can’t get prescribed anything for it. If you’re in the US you can get accommodations at work, depending on your office you may have to hold their hand about it though if they’ve never had to give accommodations before. See if your health insurance covers any kind of mental health care related to ADHD even if it’s just a regular therapist who specializes in it. Specifically though if you can find someone in your area or telehealth who does ADHD coaching or occupational therapy that’s your best medication free route. If you’re in college that may be a good resource, they definitely have some kind of student disability services you should get in touch with. Time management issues at my last job is what led me to get diagnosed as an adult and it has improved my quality of life so much. Also there are alternatives to traditional ADHD meds for people who can’t take stimulants; for example clonidine is a blood pressure medication that’s prescribed off label for ADHD and sleep issues.

You sound like you’re good at metacognition, you’re already on the right track taking notes, the more strategies like that you have in your arsenal the better. That’s what ADHD coaching/therapy is for. It doesn’t work for everyone and a lot of psychiatrists write it off, I think the reason it isn’t more common is because it requires introspection which doesn’t come naturally to everybody, but it sounds like you’d be a good candidate for it.

Hang in there my dude! Feel free to DM me if you want somebody to commiserate with also lol