Building software is actually one if the times I've felt least like an impostor (bordering on not at all?). It certainly is much better than science grad school

Building software is actually one if the times I've felt least like an impostor (bordering on not at all?). It certainly is much better than science grad school in this respect, which is likely due to fast feedback from the compiler, your tests, and your peers. Seeking out feedback at all levels that you can find it is vital not just for happiness but also for growth, and it doesn't always come in the form of a paycheck.