Let's start at the end.
I feel like I am coming to a realization of futility and its not feeling good.
Do you want to feel good or do you want to see the truth?
Why am I putting myself through insane amounts of stress and pressure if it's ultimately not going to matter?
Well, this doesn't sound like it feels good. Yes, why do you?
it still feels like "I" am influencing some part of my life. Even if I weren't, what's the point of everything?
Life doesn't need a point. Life is life-ing no matter what thoughts about it come up in the process.
I could wake up tomorrow and say fuck it, I'm not going to class anymore, screw my research, screw everything. My life's going to take an extremely different trajectory compared to if I stick to what I've been doing for the past 4 years. I'm not saying one path is right or wrong over the other but clearly my decision is impacting how my life is going. Where does that initial thought process to bring about the ultimate decision come from?
Your decisions have never been yours. They are the result of an extremely complicated interplay between genes, conditioning, coincidence, ideas you were surrounded by, hormones, and wheather. And more.
You don't decide which preferences to have, do you?
The outcome of your exams and your research is a result of conditions. There is a certain amount of intelligence, resolution and other conditions that result in a certain outcome. It couldn't have been better, and it couldn't have been worse. It is as it is, and cannot be otherwise. You never took a bad decision. You always took the best decision available at the moment, like everybody else does.
It is like when water trickles down a hill. it finds the best trajectory, by itself. Sometimes the water runs faster ("pressured"? "stressed"?) and sometimes slow.
This outlook on life certainly feels better than the assumption of a YOU which is pressing YOURSELF into anxiety attacks because YOU are afraid to make the wrong decisions.While in reality there is anxiety (the bodily symptoms) plus a thought: I am doing something wrong, I am anxious.
And here comes a caveat: If you suffer from bad anxiety attacks (world spiralling into chaos...), see a therapist, please!!!