Hi hun, I know a lot of people don't like them, so disregard if that applies to you But does she have a dummy? I think some babies just need to suck to fall asleep and stay asleep.. she might be half waking after 5 mins, realising the boob is gone and crying. If you pop a dummy in when she wakes and try to pat or rock her off, it might get her backto sleep.

HTH