You certainly are not an idiot, if you managed to do all that work up to professional standards. You didn't say how much you charged for that job, so it is imp

You certainly are not an idiot, if you managed to do all that work up to professional standards. You didn't say how much you charged for that job, so it is impossible to give assessment there. But it is almost certain you charged way too low. From what I can gather, you provided a lot of services there. It's not so much the designing and the 3D model that counts, but all the services you describe, that are really, really valuable. Because you provide a total package and one that is facing regulatore/legal. Two years of site visits alone would amount to ~50 trips. This alone would be worth 20k at least, since you also are bound for that time and cannot leave town etc. Hard to say without further details…