Bread! Explain it to me like I am 5 years old!

Have introduced almost all the allergens except wheat! Bread has always freaked me out. Two days ago, I toasted a whole wheat bread and put hummus and beet puree on it. She nibbled on it a little and was able to take a bite but not ingest. She spat it out. The toast was slightly toasted, edges cut. Today I did the same thing. She was able to bite it off but it became gummy so she couldn’t really swallow it. My question is how much do you toast your bread? Crispy, hard that she can’t bite into it? But if she can’t bite into it then that’s not really an allergen exposure. I’m lost with the most simplest of ingredient.