Somebody recently told me that she heard from an ehrliche Yid that if after doing a certain mitzva you doubt yourself it’s coming from the Yetzer hora, not the Yetzer Tov. You do the best you can and then move on WITH SIMCHA.
I don’t know if it’s applicable for everything and you do need to learn the halachos going forward if you think your knowledge is lacking, but simply doubting yourself with no benefit is definitely counter-productive. And the Torah was not given to angels — we try our best with the information we have as mere mortals — not by second-guessing everything up the chain over which we don’t have much control.