I'm pretty well convinced that those measurements of where it "should" be felt only apply to first babies.
Once you've already had a baby everything is stretched and moves around much more freely than it did before so I don't think they hold as much relevance. I was also alot bigger throughout the whole of my second pregnancy than I was in my first and my babies were roughly the same size.
Particularly when as you say your bub is measuring correctly. Everyone's built differently I wouldn't take too much notice of where the books say it should be