> But as a programmer at work, I often receive feedbacks from 1 or 2 persons at most
Oof, yeah, that's rough. It's hard to say something conclusive with little data, and most of the data is likely biased (yourself). I'd recommend finding opportunities to work with other devs. Open source is a good path forward.
Otherwise, estimating your performance is super hard. Are you right more often than you're wrong? When you're wrong, do you consistently fix your flaws? Are you learning? Are you contributing more and more business value? These are all very opaque questions, and even if you answer all of them you're likely to have gaps.
Get more data!