Yep no poo for days is totally normal! DD2 went through a stage where she'd only go once a week...but when she did, my god she did!!!

DD2 does the pulling off thing too, i think because they arent as full and let down takes longer and she gets mad that its not coming quickly enough, if i realise i try and hand express to the point of let down and then put her on and she seems to be happy enough.
Also maybe try feed her in a different position, sometimes that can help too.

Your doing such a great job hun,this BF gig isnt an easy one, but definetly worth it!