ADHD meds not working

Hi guys,
I started my ADHD medication (Concerta 36mg) on August 2nd, and today I’m completing my second week
and during the first week, I noticed a lot of positive changes and felt like the medication was really helping me,but at the beginning of this week, it suddenly felt like it stopped working,I don’t feel the same effect anymore, and I’m not sure why
My period is also 4 days late,I read that ADHD medication can feel less effective before your period, but I’m not sure if that’s actually the reason in my case,I also don’t think I’ve been taking it long enough to build dependence :(
Has anyone experienced something similar? If so, what was the reason, and what helped?

PS: I have an appointment with my psychiatrist on Saturday to figure this out, but I’d really like to know if there’s anything I might be doing that could make the medication less effective.