Texting with chick on Instagram

After a little back and forth she complained because I was taking my time replying. I said I was busy and asked for a date. She said yes. After that I have send her my number and said "Maybe i will reply you faster on whatsapp." She :"Oh really? (Sarcastic) "I wonder why you dont just you ask me directly for my number"? Me "Didnt think this should be a big thing after agreeing on meeting up anyway"? She "Thats why I was wondering."

Dont know it's just a weird shit test and she is very defensive. Thought about answering like "That's why I didnt ask." Or some AA like "Sorry, next time I will propose for it". Do you have anything better?