Hi and welcome
The majority of piggies do not like being picked up; it cuts too close to their prey animal instincts. Your girl is also a teenager now and is pushing the boundaries.
Please take the time to read the guides below; you should find them very helpful and interesting. They help you to understand guinea pig instincts and behaviours. You can then work around the instincts and use guinea pig social behaviours to interact with Emma in ways and in a frame that she instinctively understands; you can call it piggy whispering if you like. It is surprisingly effective.
Copying the methods that socially very adept piggies use with disruptive/fear-agressive new members, start with love, then assert your dominance, switch to love again. Do this a few times, always ending with the assurance that you treasure her and want her to be a member of the group you are leading. Once the hierarchy between you and her is cleared, you should have less problems.
Understanding Prey Animal Instincts, Guinea Pig Whispering And Cuddling Tips
Bonding: Illustrated Dominance Behaviours And Dynamics
How To Pick Up And Weigh Your Guinea Pig