why doesn't caffeine affect me?

Caffeine is not designed to energize one's body. Caffeine, instead, accelerates the heartbeat which, in turn, accelerates the body. This gives the illusion that caffeine energizes your body. When its effects wear off, your body is left exhausted. Then, your now-biased mind suggests coffee (or other caffeinated beverages) to "re-energize" your body. This cycle is repeated.

So, in reality, caffeine will not energize you. Because of its characteristics, it is classified as a drug. Why, therefore, would it be considered good? Money, put simply. You fall victim to this con in the belief that all will yet be well. Sugar has the same effects.
Hope that I helped!

I'm exactly the same way. It's never had any effect on me whatsoever (I still drink it because I like it!)
Not sure if this is true, but I did hear something interesting from one of my boyfriend's friends who is autistic. Apparently autistic people are not affected by caffeine, because the autistic brain doesn't respond well to stimulants.
I have been thought to have mild autism...Is is possible you could too?
Aside from that, I've no idea. I suppose everyone is different!

I love drinking tea and coffee but caffeine has never had much of an effect on me. I am a daily tea drinker now, but I went for years where the only caffeine I drank was sporadic after-dinner coffee (less than once a week) and it's never really woken me up or kept me awake at night. Sometimes it even makes me sleepy.I don't take medications that could interact with it, and I feel good after drinking it..

coffee cannot make up for not getting enough sleep or not eating a healthy diet.
Get more sleep.

Caffeine affects different people in different ways. For some people it is a stimulant, (makes you feel more awake,) for some it is a depressant, (makes you feel more tired,) and for some people like me it won't affect them at all. Drinking more and more of it will just make your body tired without it rather than energized, because your body will become addicted to it.