I feed my baby "dinner" at around 5 or 6pm, then after bath (just before bed) I give him formula. Is this OK?

The reason you're getting conflicting answers is that there IS no absolutely correct answer. If it is working for you, then it's right! Don't pay too much attention to "experts," because, no matter how much they act like it, they DON'T know everything! It's more than fine to wait until your son's next well baby checkup to ask your doctor about this.