I think, you are doing it right. Perhaps change the difficulty of your saved game and see what happens.
Yes, there are spikes in difficulty, but these are problems of the max difficulty.
I always buy things, which will be handy in the future. Things that will give me an advantage over my enemy (like artefacts). Or components, later all the steel.
Try to be near another settlement and use small caravans.
Change the environment, so when there is an attack, you have good defending points.
And use your one-use weapons.
Yes, there are spikes in difficulty, but these are problems of the max difficulty.
I always buy things, which will be handy in the future. Things that will give me an advantage over my enemy (like artefacts). Or components, later all the steel.
Try to be near another settlement and use small caravans.
Change the environment, so when there is an attack, you have good defending points.
And use your one-use weapons.