Here are two charts to help you estimate how much they actually got. It divides the chart by the type of chocolate as some types have more theobromine than others:
The Chocolate Chart Interactive - National Geographic Magazine Chocolate Toxicity Calculator - Dog ate chocolate? Find Poisonous dose.
When you texted the vet, did you ask about inducing vomitting? Most ER vets will walk you through the procedure over the phone without charging you.
I hope Bryleigh is ok.