Since you deleted your previous post I'll copy my reply below.
In short, the answer is it all depends on how you frame it. I got diagnosed a few years ago, and had some similar concerns. It was at the back of my mind for years if I had ADHD, but it wasn't until I tried Addy for the first time that I knew for sure. It was night and day. I self medicated here and there for a few months, almost like experimenting on myself, at which point I knew for certain. Talking to my parents was a process, but for sake of concision as well, detailing that part right now isn't necessary.
Fast forward to talking with the psychiatrist for the first time. I had been thinking about this question, and many others for days trying to think of the right approach - but in the end went with brutal honesty.
I disclosed my pretty regular use of weed (grew up in NorCal), but more importantly, I explained why I used it, and at that, why I used it so much. For me, it was because everything was enhanced with weed. Life, socializing, doing activities, doing schoolwork, everything was just more. And it felt right. Literally anything I could do sober, I could do just as well on weed. I knew about the idea of state dependent memory, and used weed to raise my Calc BC grade from a C in the beginning of the semester to an A by the end. No joke. I also mentioned that I have used adderall before. That because I thought/knew I have ADHD, I wanted to see if the meds would help/work. And told him about how crazy and amazing the change was. I am a naturally very expressive individual, so that helps portray the honesty frame.
Back to the point. Along with everything else I described in my life, how it has impacted me etc., my psychiatrist responded that me smoking weed and how/why I did it makes complete sense. He even complemented me on the productive way I used it. WTF right?!
Turns out some people with ADHD will have a high affinity to dopamine seeking behaviors. My brain wasn't getting or naturally producing the amount of dopamine it needed, so I was naturally drawn to many activities that gave me my dopamine fix. Weed just being one of them.
Even till today while I hardly use weed anymore, it is still very much a part of my life. It helps a lot when I am taking addy breaks as well. For when I was smoking a lot, it was addy that got me break the habbit/addiction. If I took addy I felt absolutely no need/urge or even want to smoke weed. Probably because my brain is getting the dopamine it needs. Now weed helps when I take a break from addy. (I have a previous post about being physically dependent on stims, shit sucked, wouldn't recommend, am better now though)
TL;DR Know how to frame the topic so this can even act in your favor. Frame it with the why's and because's.
If he/she is a self-respecting psychiatrist, they will recognize at the very least that you know/believe you have an issue, and will try to work with you.