Help: placebo or effectiveness

I’m on Vyvanse 60mg and I’ve been on it for 3-4 days now, and I know I should wait a bit longer, but sometimes I feel like it works and sometimes it doesn’t. Like, I was in class and I was able to focus but I still drift off. Before hand, I still drifted off but i could for the life of me not focus, and now I can remember things almost on a dime. Example, before Vyvanse I couldn’t remember the day or time when asked, now I can. However I can’t feel these proofs if it’s effectiveness is just a coincidence and I’m placeboing myself into believing Vyvanse is better than adderal. How can I know if this is a placebo or not?

TLDR: idk if my Vyvanse works, how can I know it’s not a placebo