YOU are the professional. You are the one responsible for ensuring a true meeting of the minds. If you didn't do that, you didn't do your job.
As SecretAgentBaker mentioned, I expected to see the buttercream flowers you offered. There aren't any. Did we misunderstand?
I, personally, don't conduct "business" by text. If the client sends me a text, I follow up on an email. If the mother, or other designated person, makes a change I also confirm in email. That can be very messy as you are learning.
I think it's important enough to mention again that I still have no idea what this order was supposed to be. Did you?
If I were in this situation, I would pick up te phone and have an open, honest discussion with her. Try to smooth things out but also be firm about what she did receive. You absolutely should be compensated for your work.