This is exactly what I think is going on, except what if I only think that because it means the medicine isn’t at fault. AM I really more irritable with everyone or only with her?
Of course it’s hard to say to her, “oh, well, it IS the meds, but only in the sense that now I feel more confident about myself and I’m not willing to put up with the way you talk to and about me.” I mean. Being on these meds I’m less likely to react defensively when she says something that in the past might have made me feel ashamed. But I’m also less likely to duck my head and turn the other cheek, so to speak, which was historically my other response because I just didn’t feel like arguing. I’m not sure my newfound confidence is actually HELPFUL or not, but I definitely feel way more sure of myself. In the past when she commented on how I forgot something or didn’t follow through on something, I would usually just apologize and try to move on. (I say try, because she will harp and harp and harp over and over about what I didn’t do and how it was important and didn’t I understand and on and on until my head would explode with anger or I would just meekly do what she wanted.)
I wouldn’t mention the ADHD, because I didn’t want to hear her dismiss it. Now I say something like “Yeah, that ADHD rearing its ugly head again.” Which sets her off, because she then accuses me of using it as an excuse for everything. And then it becomes and argument. And I don’t back down any more.
Every time she says something along the lines of “Well you just have to do it. Why don’t you just do it?” And I reply, “I can’t JUST anything. It doesn’t work that way.” These sentences are both completely useless for actual communication, and have the added detriment of putting both of us on the defensive. I haven’t figured out how to break this cycle. How to make her hear me when I say, I wanted to do it. I would have done it if I could have. I didn’t CHOOSE not to do it. It just got away from me.
So TL;DR you hit the nail on the head. I fell calmer and more stable on the meds. I think I push back more when she’s insulting and she sees that as “angrier”.
P.S. I want to make clear. I love my Mom and I know she loves me. I wish I could find a way to communicate better with her. She doesn’t deny my ADHD. But she also doesn’t seem to understand it or even want to. She doesn’t mean to be so controlling and judgmental. She’s just trying to help me because she loves me and wants me to succeed and be happy. She doesn’t understand that her “help” does more harm than good because all it does is tear me down. She is unable to allow me to make choices and do things that she thinks are “wrong”, so she tries to make me do things the “right” way, i.e. her way.
or at least the eating one. I’ve learned that just cause I don’t feel hungry… dooooesn’t mean I can’t get hangry 
