When I latch how do I know if my baby is shallow latch or deep latch ? When my baby latch the milk always end up on her cheek or flow down to her ear is it because she is not swallowing?

From your descriptions, reckon baby isn't latching properly hence the leakage. She probably didn't latch well and unable to swallow. This article has a list of signs you can look for to see if baby is latching and swallowing properly. One of the more interesting signs is that baby's ears will wriggle and move actively when he or she has a good latch. A good latch would mean the muscles connecting the ear and the mouth will be working actively. http://www.askdrsears.com/topics/feeding-eating/breastfeeding/rightstart-techniques/baby-latching-and-sucking-efficiently-how-tell