I wouldn't get hung up on strum patterns. If singing and playing is your goal, focus on simple strumming and getting the playing automatic, and singing becomes easier. Watch YT vids of people covering tunes you're learning and you might see or hear alternatives that work, and are easier.
I think it was well over 2 years before I could add vocals to songs, and I started late on tackling those, I spent most of the BC working on the techniques. I till find some rhythms and vocals hard to put together, others click quickly.
I wouldn't view strum patterns as the template for every song. There are a very few 'staples', but the more songs you learn, the more you realise playing it like the record would require pages of strum instruction. See Justin's Wanted Dead or Alive lesson to hear his take on strumming and trying to verbalise tricky patterns.
The patterns are to get people started in hearing and playing rhythms rather than, "This Bon Jovi song uses pattern 46…"
Some people get to the stage where they play a rhythm that works for a song and the way they vocalise it, whether it's the same as the record or not, yet is still instantly recognisable.