Physics Grad Student hitting motivational wall

I am currently a experimental Nuclear / High Energy grad student at a larger American university. I have finished classes, and I am well established in a research group. I've done well in my courses, passed all the relevant qualifying exams, and would estimate I'm in the top third of my class, although hardly the best. (This account, however, is a throwaway, as I'm somewhat active in this subreddit.)

First off, I am not bored with Physics. I still love the science. I'm good at my sub-projects, and I'm contributing to our collaboration. I'm in a great group, with a supportive advisor and easy-to-work-with researchers. I think I lucked out, in that there is not another group at my university that I would prefer.

However, the last couple months, my motivation has taken a pretty big dip. I finished my last course, so any physics I learn from here on out is entirely on my own. I'm OK at subatomic and H.E., but I am still completely lost in QFT, despite two semesters of it. I've never taken any formal programming, and sometimes my coding or Linux abilities seem like I'm just winging it. I try to read up on it, but more pressing hardware and analysis matters usually take precedence. I know I'm not a theorist, but it is extremely demoralizing at times to be stumped by some basic physical idea, or to have a conversation with an academic peer, only to be blown out of the water by the superiority of their physics knowledge compared to yours.

In addition, the grandiose plans I had in physics (similar to what all motivated, young undergrads have, I am sure) are starting to bump up with the realities of the field. I am not going to be the next Feynman or Dirac or Gell-Mann, and I won't be winning a Nobel Prize or anything like that. The skills and decisions required for that level are decided way before my current time in my career. I'm hardly a genius. I just have a slight aptitude for math and physics and a lot of training. However, it seems like the work I do is extremely interchangeable with the work any other physicist does.

I could be successful at a bunch of different aspects of my field, and become a passable and employable physicist, but then I would not be contributing to the cutting-edge of my field. Or I could specialize, try to push deep enough into a sub-field to put a dent into the boundary of human knowledge. However, with my aptitudes and abilities, there will be likely dozens of scientists out there who could surpass weeks of my own work with one motivated day of their work.

So, that is where I am at right now. Too skilled to fail, but not skilled enough to make an impact. I didn't know if anyone else on this subreddit had similar crises, or any advice in general for a student at my level.