I can't get myself to study

Sorry if this is the wrong subreddit but this feels like my best bet atm

I (16m) have some pretty big exams coming up in a couple of months that I desperately need to get off my ass and revise for but I just cannot get myself to do so, anytime I get close to actually studying I look at everything I need to do and get really overwhelmed and have a meltdown

I'm trying my best and my mum has tried to help me with it (setting up timetables, splitting work up into chunks) but it's just not working and I'm just getting more and more stressed about this. My mum keeps on acting like it's my fault bc I haven't been trying hard enough and I don't know how to tell her that I'm trying my best here and I'm not putting it off to be lazy I'm just constantly stressed and overwhelmed, which isn't something I want during the holidays (I have 2 weeks off school and I'm about halfway through the first week off)

None of my friend's advice has been working and every single study guide I find has basically gone "having adhd will make you bad at studying, so don't do that"

I'm not formally diagnosed or medicated for adhd, I'm on a wait list for a diagnosis but won't get one before my exams but that's the theory me and my parents have been going with and most adhd tips tend to work for me, so I need any study advice for unmedicated adhd please 🙏