I'm afraid you are believing the 'breed hype' and are frightened of your own pup. Yes you do need to be firm with a Rottie pup, you also need to be fair and consistant - but above all remember - she's just a puppy like any other puppy. She may be a pushy little madam - she might be like that her whole life - but you need to set boundaries for her to live by and praise her good behaviour and ignore her bad. Please google NILIF - this is Nothing In Life Is Free- and its the sort of training that a lot of Rotties respond to. As soon as her injections have been done get yourself booked into a puppy class - this will do the both of you a world of good.
I've gotta go out now but I'll be on later on
