Not alot for a 6 week old I'm afraid. Its OK to give her some cooled boiled water, some babies need extra fluid which will make it easier to go. The consistancy of peanut butter is OK, and babies do 'concentrate' to go - you can usually tell when they're doing it. As long as she's not crying out in pain I would try giving her a little extra water in a bottle between feeds maybe once or twice a day and see if that helps. Wind out is great in whichever way so that sounds like your doing the right things.
A change in formula could have caused the consitpation, I don't know what the choices are where you are but ask other mums what they use and how their babies are getting on with it. You'll know then if the problem is particular to you.
However if she is ever crying out in pain to go then take her to the doc for a check up.
Its hard being a new Mum, My son was formula fed and is as strong as ever now, we were worried about constipation and colic and ended up at A&E just to be told he was fine. So your right to keep watching and asking advice, Sound like your doing well though! And congratulations on your baby!