Let me tell ya, I know many people who didn’t complete their studies within the ‘normal’ amount of years. In physics, I would say those who did were a minority. I myself finished my studies two years later than I was supposed to. Still got into a PhD. It’s true, it’s an insanely competitive field and it’s never easy. But I think you have to keep in mind that the science world is a bit different than undergrad/graduate courses, being older doesn’t really matter. What matters is the quality of your work. And comparing yourself to others won’t be very helpful to you. I lost one year due to depression, another to laziness and procrastination (and self doubt, and all of that). I think what got me through is what my high school math teacher once said to me: “the drop will dig into the rock”. Do all you can, but do it. Best of luck!
“You ask: what makes man great? Is that he re-created nature? That he harnessed forces of almost-cosmic proportions? That in a brief time he has conquered the planet and opened a window onto the universe? No! It is that despite all this, he has survived, and intends to continue doing so.”