deasy, you MUST relax about all of this. it will affect your supply if you continue to worry about it all.
first: as others have said, it is perfectly normal for babies to have watery stools. they only have liquid intake, it would be very strange for them to have anything solid in their poop if all they are having is liquid.
second: it is also normal for some babies to poop each and every nappy. it is also normal for some babies to only poop every day or two! there is a HUGE range of normal!
third: for nappy rash, buy desitin. it creates a barrier between the bottom and the liquid and prevents rashes from starting (my girl got terrible rashes if she was left even 5 minutes with a wet/dirty nappy).
fourth: some babies are efficient eaters and only EVER suck for 5-10 minutes. both of mine were like this. if your baby is feeding regularly and is producing enough nappies, then you are doing it right.
lastly: you do not need to make another appt with the MHC. the nurses will ALWAYS meet with you to discuss any issues before baby gets the injection.
you need to have confidence in yourself and your abilities.
good luck!