Concerned about lack of wet nappies - 4mth old

DS has just turned 4mths old but his lack of wet nappies has been bothering me for probably over a month now.
He hardly ever seems to have a wet nappy and I cannot remember ever changing a heavy wet nappy ever. Today I thought I would really monitor his nappies closely, by lunch time nothing, if he did pee then it must have been a really small amount, I could not feel it, see it or smell it. He was in a disposable so I put him into a cloth nappy to see if maybe that would be wetter, I thought the disposables may have been too efficient. I put him into this at 1:30 this afternoon and checked it throughout the afternoon - nothing and tonight at 6pm still nothing.
I have been feeding him every 2-3 hours to try and increase and keep my milk supply up as I has been having huge troubles with my sleep and quite stressful things happening in my life, you would think that is plenty and would produce wet nappies. He doesnt poo everyday but definantely poos every second day and could be 2-3 times that day.

To me he seems settled, nothing unusual maybe a bit clingy but I think thats just him. I cannot see any signs of dehydration, his fontanelle is fine etc. I have an appointment with MCHN on thursday.
Hope someone can help.