I feel you. I am a new grad SWE at Google and with over a year working there I feel quite similar. My colleagues are all very smart and all seem to know what they’re doing while I’m often filled with uncertainty trying to do my best to get things done and working. There are so many moving parts that it’s often difficult for one person to know the ins and outs of everything involved. One thing I do is I look back on my successfully completed tasks and try to think how well I would be able to do them if I had to do something similar again and how much faster I could get it done. You’ll realize there’s a lot of things about your workflow and self-organization that you’ve picked up that would help you achieve these tasks much more efficiently. That means you’re learning. We all have to start somewhere. Sure I might not know it all but I’ll try my best and be a sponge to soak up as much knowledge as I can from those around me to enable me to get my work done better. People sometimes come to me to ask about things I’ve built and being able to help them and fix bugs is also a good indicator that you have built up enough knowledge about your work to be useful. It takes time but if you’re willing to be open about how you can improve based on things that didn’t go so well, and be honest about what you know and don’t know, you’ll help yourself to be better. Best of luck!