Agree. Sounds perfectly normal. Mine were similar at that age. Babies vary so much more than the books suggest.
If everything else is going well, nappies, weight gain etc like Veet said, then you are not doing it all wrong. And even if those things are iffy, it is not because you are doing something wrong in feeding him when he wants and needs to be fed. That is exactly the right thing to be doing.
Your post sounded so familiar - it's so hard having a new baby, and the fear that we are messing it all up is often hovering in the background - but it sounds like you are doing fine. I was worried about it and tried to space out feedings for while - resulting in dh pacing for hours with a screaming baby. After we abandoned that approach and just followed her cues/demands (!) it was so much easier.
The feeds became much.more spaced out, although she never really developed a noticeable pattern or routine, so when it got to weaning onto food, i found the books' suggestions of dropping a feed at a time, say, baffling - but, although it was haphazard, she gradually ate more and had less milk, and ... the point is that the books describe some sort of simplified model of an average baby.
And you'll definitely get time for a hair cut one day!