Doubting my ADHD diagnosis

I’ve always had the idea that I had ADHD but didn’t get evaluated until I was about 16-17. I’m 19 now and haven’t really got much treatment for it due to co-morbid OCD. I’ve always heard caffeine calms people with ADHD down but that hasn’t really been the case for me, I also have never really been hyperactive outside when I stim. I know there’s a subtype called inattentive ADHD; how do you guys with this specific subtype feel, act, does caffeine help, and if you have co-morbid OCD (specifically pure O) do stimulants help or hurt?