Above you can see my baby with a bad latch. His nose is buried in my breast. Another sign to look out for is the baby being right on the end of your nipple (it hurst heaps more to have them latched this way too).
So some other signs your baby has a poor latch are:
The video below shows twins feeding. The one on the left is latched well, but the twin on the right isn't and is complaining - they don't get much milk when they're latched badly.
So if you think you have a bad latch what do you do?
Firstly check out your positioning - see this video if you'd like to change your breastfeeding positioning. Make sure that if you do try something different with positioning that it does actually feel different on your body - if their head is in the same position on your arm and their body and legs feel the same on your body then it's likely you haven't really changed anything!
Changing your positioning will often help the nipple pain, but will also mean their lips don't move as much and their nose won't be buried.
If you're worried about them not opening their mouth wide or sticking their tongue out much then baby led latch might help you reset their reflexes for breastfeeding.
If in doubt, go and see a lactation consultant (or get one to come to you). If they don't seem to help, get a second lactation consultants opinion - it's well worth finding the right person to communicate well with you