like the others have mentioned the initial pain is normal. it can be a combo of the vacuum force of those little mouths and the milk flowing through. it will get better as time goes on and she gets really efficient at the sucking.

also as for the end of feeds i can HIGHLY recommend that JUST before she comes off you gently pry/push down with your index finger the boob/nipple part that is just at the edge of her mouth, this releases the pressure that she has created and means that she doesnt just 'snap' off itms. (i hope i explained that ok lol).