Haha, I've done the same thing and avoided studying in favor of doing more interesting things. You can try using a lockdown browser extension or focus app that blocks certain websites during your study times. It works sometimes, but I frequently find myself circumventing the system.
What I do now is avoid certain websites that I know I'll get lost in (Youtube, Facebook, etc.) by going on them as little as possible when I'm only my computer or only accessing them on my phone. Essentially, I make using them as difficult as possible so my brain doesn't want to bother with it. I'm currently unmedicated, but I found taking meds made starting tedious tasks a little more bearable. Good luck to you!
I have a couple of subjects that don't accept extensions; your work just loses marks when it's submitted late.
I really struggled at the start of semester, because I had all these pre-lab questions to complete before lab, workshop tasks due at midnight, other lab tasks due on Friday and Monday, etc.
I emailed my lecturers and said basically, "Hey, I just got diagnosed with ADHD and I'm trying to fix my life. Can you please tell me what tasks are due on what days?"
To their credit their replies were very understanding and they gave me the due days. I put everything into ToDoist (https://todoist.com/app/today) and it's helped me keep on top of my study habits. And my exercise habits too, because I forget if I went for a run or did a workout on what day. Highly recommended!
Read Elements of Style by Strunk. Here’s a link to it on Amazon. You will not regret taking my advice on this. The professor I did research with said he thinks everyone should read this book.
It’s a grammar book that’s short and has examples. It reads like a story in a way. I hate reading but I was surprised by how much I enjoyed it and it only took me a few hours to get through. I have specific learning impairment in reading so I struggle with reading quite a bit, but it was definitely an easy read and was a life saver when I was working on my SOPs this past month. It focuses on how to convey your points in the most succinct way possible.
The version I linked has pictures and illustrations too, which my ADHD ass thought was a nice touch :)
https://www.jetpens.com/Gakken-Write-White-Whiteboard-Notebook-A4-Gray/pd/34485 I found more sizes though a proxy service since they were available on Amazon Japan. https://www.amazon.co.jp/-/en/Gakken-Sta-D15042-Whiteboard-Notebook/dp/B096LXRFFV (this is where they show the pic of using the clear sheets to write on) It won't show you if they're available unless you toss in a JP postal code since they dont ship to the US. I just googled a JP company and copied it from there.
I’d find a place to study that is not in your home, maybe there is a library near you. What helps me is dressing up a bit nice/semi formal and going to the library because it tricks my brain into thinking i’m doing something more important than I might be. I would also just do 2 hours at a time. Don’t bite off too much and try to study for 9 hours. Just do 2 hours in the morning, 2 in the afternoon, and 2 before you sleep. Try to be task oriented instead of time oriented too if that helps. I have bought these timer cubes (https://www.amazon.com/Feilifan-Exercise-Management-Countdown-15-20-30-60/dp/B08PB9W3GT) which have been super helpful in terms of getting me started. Hopefully something I said sparks some motivation and best of luck!
Microsoft has comparable things which you can use for free
https://www.microsoft.com/en-gb/microsoft-365/microsoft-to-do-list-app
And even better when you combine with....
I use this app called Microsoft To-do which I update on Sundays to prompt me during the week. You may want to give it a whirl. It is quite simple!
Book:
Detox Your Writing: Strategies for Doctoral Researchers. https://www.amazon.co.uk/dp/0415820847/ref=cm_sw_r_u_apa_fabc_Jf40FbPCFX4JH
This book is brilliant and would reccomend it for any level, not just doctoral studies. Their section on imposter syndrome is especially good and has picked me and other neurotypicals out of a rut. It's expensive, but can likely be found via a library. PM me if you have trouble finding it as there are e copies floating around online.
I had the problem where I'd take my meds and then 10 minutes later, look at the bottle and think, "Did I just take that or was that yesterday?", so I finally got a pill box. I got one where the little capsules are separate so if I go away for a night I can just take a single day's worth instead of the whole thing.
https://www.amazon.co.uk/TimerCap-Stopwatch-Medication-Reminder-Mail-Order/dp/B00ECK8KFG
Timer caps. I posted this on another thread recently, but these are great.