Sorry you are having issues with your build. What kind of mistakes?

If your problem is with picking materials/colors, maybe you can find a good Interior Designer that will consult with you for a few hours to help you confirm or adjust your choices.

What part of the process are you in?

Are you feeling overwhelmed by choices?

Are you still designing or have you started building? How do you know you're making mistakes? If it's just designing, pencil and paper are cheap. If you're already building, few projects go perfectly. You are not alone.

As stated above, interior designers are available for consultations for a couple of hours at a reasonable cost. They can help with design choices so that you don't select something you might later regret.

I think we need to know a lot more and to begin how many homes have you designed? yes it is overwhelming and you need to get an architect or a least an interior designer on board. If it is choices of finishings you are way to far out to know what they will be. So provide us with some info please.

Are you working with an architect? That would be a good move to make if you have no experience in designing homes. If anything, get a set of renderings or a 3D model made of your plan to help you envision the full project before you commit to anything, You don't want to waste your time and money on poor design choices.

join the building home monthly forums for folks going through exactly what you are going through. it was a lifesaver during my build..and i still check in with folks. And the tone is a tad kinder than general threads cause building is stressful.

Best of luck.

https://www.houzz.com/discussions/6021744/november-2020-building-a-home#26287602

" . . . but I keep making mistakes! Is this a normal part of the process?"

Yes it is a normal part of the process. By the time you have designed your 500th home you stop making mistakes and start creating options. There are people that do that for a living and are licensed by the State. I am 90% done tiling my bathroom floor, wainscot, and tub surround. It is turning out very nice, but I should have hired a professional. Not as young as I use to be.