I feel stuck and don't know what to do

(Reddit is usually not the place I'd come to for advice, but I really just need some advice without being judged)

First year of college, one of my professors said there were openings in his lab and he'd love for some of his students to work for him as interns. I volunteered cause his field of research felt interesting to me then. I cleared the initial interviews and got in. Its unpaid but if interns do well, they get co-authorships, sent to conferences etc.

Recently, I have started feeling like I don't want to work there. I have been working there for about an year. I have to go to the lab after classes end and many a times I'm too tired to do it. I show up anyways and I really don't slack off. I stayed back for about two weeks during my summer vacations because I was helping with a project. The project ended up being dropped due to some reasons and that was the end of it. (We were told during the initial interview process that we may be asked to stay back during vacations).

I feel like I go there just to waste my time. They give the interns mini projects sometimes to work on. Since the project I was working didn't work out, I have nothing to do.

I feel like at this point, I can't quit either. My professor told me he has high expectations from me and that I'm one of his smarter interns. He's already pushing me to do a btech honors from his lab and its not just him, its also the rest of the team. I feel like leaving would be disappointing them but at the same time, I dread going to the lab everyday.

Its like I'm stuck in a loop. I hate when I'm given assignments, I do them well and get praise for it, I feel like things might finally work out only to be handed more assignments and hate doing them.

but a part of me doesn't want to quit because I've invested too much time in this internship to end up with nothing. I stayed back after classes, during summer vacations, made damn sure I carried out experiments properly, spent hours researching etc. I'm scared all of it will amount to nothing and I'll fail at this too.

No one sees efforts, just results and if I can't produce that, what am I doing. I feel like this is the only thing giving me an edge over other kids. I feel like I'll fall behind if I quit. I feel conflicted and stuck.

Today, I had to do some work for an Mtech student. I was too tired after class but went anyways, ended up missing going to the gym and ended up spilling some chemical on a new t shirt and now its ruined. I tried talking to my mom on the way back but I couldn't keep myself from crying so I had to end the call.

I feel like if I quit, all this effort and all sacrifices would go to waste. But I'm working for the promise that something might happen. All this effort might count for something but I might as well be wasting my time so I really don't know what to do.