Hi! I have ADHD and I used to take ritalin, but now I'm on dexamphetamine ("attentin") because that doesn't contain any traces of gluten or gelatine. I have tried meditation both with and without my medication. My preliminary conclusion is that it works best when I take my medicines as I'm supposed to during the day. However, jhana practice seems to work better in the evenings and nights when the medication is out of the system. Not taking the medication during the day does not help for me, because that makes me develop patterns of both distraction and dullness. 

Ritalin is designed to get out of the system in the evening. For me it was very early in the evening. 

I'm just checking in as someone with ADHD & a meditator. I haven't got any of this figured out. Been off meds for years after some crazy side effects (there was a collapse of other things such as regular eating and sleeping). It's been a hard ride as someone who wants to benefit others and has an IQ over 130 and crashed out of university, working precarious entertainment industry jobs. 

I believe I got into meditation seeing footage of zen monasteries... wondering if "the military" would fix me up but not ethically being ok with the whole business of killing people, came across similar discipline for the benefit of compassion. Unfortunately no residential zen monasteries in my part of the world. 

I've found the structure and discipline of long retreats very beneficial and extremely joyous. usually a 2-3 day adjustment period and I'm good to go 20 - 30 days. I've even thought of long term ordination, at the moment I'm not sure if that is because I'm wanting to live the spiritual life or if it seems like the only option for me to control my ADHD and engage in a livelihood that is for the benefit of my own understanding of the mind & suffering (which will hopefully culminate in knowledge that can benefit others).

I've also thought of being a nurse or med-school (however significant doubts about the later with my ability to finish, but I know Gabor Mate has ADHD and finished med school - great author BTW if you want intersection of family medicine, ADHD & contemplative traditions)

I find keeping it in daily life to be a struggle, any tips here greatly appreciated  

I don't have any answers, and share many of your questions  

"My anxiety: that ritalin will be detrimental to my ability to enter deep jhana, to gain insight, to experience transformative non-dual awareness." 

FWIW one of the deepest and most transformative experiences that made me go "wow, this buddhist path is really something" I've had was early on sitting at a zen centre "just sitting" / shikentaza, and I was under influence of dexamphetamine [1] as I was regularly taking it daily, I've had lots of fireworks off the medication too since. It's not necessarily the case that the "fireworks" type experiences are the "deep" experiences or insightful ones, but certainly that early experience was.... seeing that the mind of awareness was the mind of compassion, and this mind that was aware was both me & and not me, or not even any of this (these being just concepts arising in the mind, or 'no mind' hahaha it also made me reflect on everything in my life that lead up to just that point in time with immense gratitude & I felt incredible good luck and fortune. For me, this was a "deep experience" and it seemed to repeat the next 3 times I visited.

I would say that definately counts as a 'non-dual' experience, so don't stress it. Medication or not medication may just be a form of doubt (one of the hinderances)

Speaking of, read about the 5 hinderances, the balancing of them (and the seven factors of awakening) . This can be done in any state of mind, reflecting on the quality of the mind as it is at present and accepting it, knowing it.... the path and recognition is beyond any particular quality of mind.

Unfortunately, perhaps due to ADHD, I didn't keep up my regular visits. Wanting a longer term exploration I went off to a Goenka retreat, figuring that it was the buddhist tradition so another way of coming to the same understanding, not so sure of it, but it was a different type of experience or insights that I had on that retreat. 

[1] Dear reader: it was not *because* of this - you must understand that to someone with ADHD taking their presribed meds is akin to Coffee but more effective and perhaps less jittery with them. This is just regular neurochemistry & routine for me at that time. Do not take dexamphetamine and hope for some insight experience, I can tell you that is just some craving for 'better' experience.