And I’m going to have to start taking it in the afternoon.

Are you taking them in the afternoon because that's when you need the effect, or to try to get sleep? If it's the latter then that seems counter productive and would probably make it significantly worse. The half life is apparently about 9-10 hours so you want to make sure you're taking it like 10 hours before you want to fall asleep. Are you on the IR "regular" Adderall or the ER? You might get more bang for your sleepless buck on ER, or just a different drug all together. My friend has better luck on Vyvanse.

I'm ADHD but I've never been prescribed meds for it. (although I do drink a lot of caffeine to compensate) The only way for me to get good sleep is to be RIGID with my sleep schedule. I'll take a melatonin about 1 hour before I want to get in bed. Then I get in bed about 30 minutes to an hour before I want to fall asleep. Staying in bed awake too long can be counter productive. I also need background noise to fall asleep so I'll play a long video that I don't really care about/I've already seen and isn't too interesting.