did any of you get any sideeffects after drinking caffeine while being on meds?

no.

my meds to date:

Adderall IR 20mg in the AM and 10-15mg in the PM.
switched to: Adderall XR 30mg in the AM
switched to: Dexedrine 15mg in the AM and 15mg in the PM
back to : Adderall XR 30mg in the AM

*now going back to the IR, but haven't started that yet, and so is quite likely irrelevant and useless to point it out here*

My caffeine usage is typically such: 2 diet cokes (*cans) in the morning, with at least 1 in the afternoon, sometimes 2 if I'm feeling pokey.

Once in a blue moon I'll throw in a mug of coffee, but only one in a day. If I'm out and about, diet coke from fast food.

So my caffeine consumption is minimal, but I've never had any adverse affects, other than the expected "wake up" that I was going for.

Yes. Caffeine just interfered with my meds (amphetamines - Adderall/Vyvanse/etc.) and kind of threw me for a loop. It's not really necessary to take caffeine when you're taking amphetamines (and can actually be counter-productive).