Lower dose, or maybe try a different brand/prescription. Talk to your doctor about the symptoms, and especially, let them know about how you really like how it works, and how it ended up working for you, but that you tended to crash after it wore off, and want to know what would be a good next step, or a good thing to try next. It's possible that taking other meds may help with it, or at the very least lessen the force of the crash--anxiety has been a common symptom that has come up for me while dealing with my ADHD and meds, so maybe a type of anxiety medication may help.

But, it also sounds like you might not have had enough gas in your tank to begin with, and that's why you felt exhausted. Sometimes, if I were take my focus meds after a night where I pretty much didn't sleep, my hyperactivity symptoms would increase, and it'd be insanely difficult for me to sit still, and/or focus (I bring this up just to show how not having enough of these "resources" in your body while on meds can greatly affect how the meds work for you). Try getting more sleep, and remember: for adults, you should be getting about 4-6 sleep cycles a night (3 stages of Non-Rapid Eye Movement, 1 stage of Rapid Eye Movement), and each cycle can last from anywhere between 90 minutes, to 120 minutes. (You may want to figure out how many hours of sleep it take for you to feel well rested, and try to figure out how long your REM cycles likely lasted during that (it'll be rough calculations, since each progressive REM cycle is supposed to last longer than the previous one), so you can then determine how many hours you may need at the very least, every single night. If you generally only need around, say, 8 hours of sleep, I'd say you're closer to that 90 minutes per cycle; if you're anything like me, and you can sleep from midnight or somewhere between 1-3, all the way until like 5 pm, you're likely closer to that 120 minutes)

Aside from sleep, make sure you're sufficiently hydrated, eating-well (don't just eat because you're body is screaming at you that you're starving--make sure some of your meals are kind of on the "heavy" side!), and take breaks to prevent yourself from burning out and/or causing minor to very serious health issues just from stress. You'll have a lot of energy for the meds to burn, and there will hopefully be enough afterwards for there to be either no crash, or not as serious as one.

And take this from someone who never liked naps growing up, couldn't sit still for them or actually fall asleep, never was tired enough for them, etc etc... The last times I had taken naps in the past few years has been after the first day, after getting home, of pretty much every level of high school, except kind of my senior year, and it was because I hadn't gotten enough sleep before, was suddenly back on my focus meds, and had had to deal with a shit ton more people after spending pretty much the entire summer away from everyone. Do you know what was /now/ the last time I took a nap? Literally just a few days ago. I've been going to bad a really bad times (my roomie also keeps staying up till like 2 or 3 am), and I have to wake up for very early morning classes (8:30 AM, with my alarms ringing to make I would wake up and STAY awake from nearly 6:30 AM all the way up until when the class is meant to start, and with almost everything being a 15 minute walk or more away from my dorm, I've been using a lot of energy. It's actually been really nice being able to do that (even if more often than not I end up staying asleep for like 2 hours or more), and it's a really good way to give your body a little jumpstart if it needs it

In any case, I hope you are your doc are able to work out something that works for you! Good luck with that!