You will be fine! His ears should be OK too especially if you breastfeed. And I have found that
a) Young babies tend to sleep most of the flight
b) People are actually much nicer than you think about babies - and if they are not - well its THEIR problem!
I have breastfed on loads of flights now and nobody has given me a funny look yet
- Try and get an aisle seat and if he has a dummy - get a strap to keep the dummy on him. (speaking from the experience of climbing under seats to recover a dummy with a five week old!)