It seems that your exposure to vocabulary and recitation has given you a large vocabulary of your own.
If this mechanism, of reciting, works for you, then perhaps reciting standard sentence structures, each time changing the words used, for other words, with the same parts of speech, might work to learn/make natural patterns. That is swap nouns for new nouns, verbs for new verbs, maybe swap conjunctions.
For simple example
The cat sat on the mat as the mat was warm.
The dog sat on the mat as the mat was cool.
The horse stood under the tree as the area was cool.
It may lead to funny sentences, but maybe that will make the patterns more memorable. When the pattern becomes something you know, part of you, then you will use it naturally.
I think you are right: getting existing patterns from examples, in texts or articles is a way to see new structures.
I think with complex sentences, the answer is alway divide and conquer: break it up. Understand each part. See how the parts are connected.
Sorry, I have little advice as I am not as good at languages as you.