i was told to feed for a minimum of 20mins the first side then let bub decide how long on the other side ie if she only wanted 5 mins thats ok if she wanted 25 mins thats ok too, to ensure the breast is fully emptied and this will help supply as well as prevent mastitis and bub may not need a top up at all. i comp fed too it is do-able. it sounds like your bub is doing well and youre doing a great job and doesnt sound like you have a supply issue at all. 60ml is a good amount to be getting this soon, plus as others have said expressing is not an indication of supply. goodluck