There are no rules how often or for how long a baby should nurse. Let the baby determine his own feeding schedule and things usually come right, if the baby is suckling and drinking at the breast and having at least 2-3 substantial yellow bowel movements each day. If that is the case, feeding on one breast each feeding or at least finishing on one breast before switching over will often lengthen the time between feedings. Contact the breastfeeding clinic with any concerns, but wait to start supplementing. This means nothing and should not influence you.
Most mothers have plenty of milk.
The problem usually is that the baby is not getting the milk that is there, either because he is latched on poorly or the suckle is ineffective or both. These problems can often be fixed easily. The baby will take a bottle after feeding. This does not necessarily mean that the baby is still hungry. This is not a good test, as bottles may interfere with breastfeeding.