bottles

My little one has a milk allergy so he needs to be on formula for a little longer. He still takes it in a bottle because he won't drink it from a sippy cup. He will drink water from ilthe sippy cup but that's it. How often do your little ones drink formula/milk? and are they still taking it from a bottle. also he won't hold his own bottle I have to do it. also how many oz per bottle or sippy