I'm Losing Faith in Myself as a Researcher

So I've been working on this project for the past three months. It's supposed to be my thesis and it revolves around finding new data sets that could potentially overturn some longstanding theories about climate change patterns over the last century. I've spent countless nights poring over old scientific journals, trying to find any inconsistencies or unexplained phenomena that might lead me in a promising direction. But here's the thing: I'm starting to feel like I'm grasping at straws. Every time I think I've found something significant, it turns out to be just another footnote from someone else's research, which already supports the current theories. It's getting demoralizing and I find myself questioning whether my entire premise is valid. I know that as a grad student, it's crucial to keep pushing boundaries and exploring new avenues of thought, but there are days when I feel like maybe I'm just not cut out for this kind of work. Maybe all the brilliant minds have already picked over these topics so thoroughly that there isn't anything left for someone like me to discover. I've even started telling friends that I'll probably end up changing my field soon because it feels like I'm destined to either fail spectacularly or contribute insignificantly. Am I being too hard on myself? Or is this just a normal part of the academic journey where you hit walls and have to figure out how to push through them?