Why does my dog bite and growl at me when I try to pick her up?

Situations like this are complicated and it's hard to give the best advice without being able to observe the behavior and walk you through things. Sometimes this can be true aggression. Sometimes this is related to Emma not wanting to be moved/handled. The latter can sometimes be treated with counter conditioning to provide a more positive experience that Emma will want to happen and thus will respond to.
True canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Best of luck.