AITAH for flipping out on my mom

I am 15f and I just had a really stupid argument with my mom. She picked me up an hour late from work knowing I had a class in the next few hours (I can’t legally drive yet without an adult) she said sorry and justified why she was late. I didn’t really care about that just saying sorry was fine and her justification made me frustrated. I said that her being an hour late was annoying and though I’ve been late before for other things on her end it’s never more than 40 minutes. She got a offended and said I could just walk home (I live far walking) or she could purposely make me wait if I pissed her off. She also said i was a spoiled brat and started mocking me when they upset me and tell me how I was victimizing myself. I asked her angrily to stop and said sometimes she was very difficult despite how nice and caring she is. I feel terrible for flipping out, but I don’t know what else I would’ve done after being egged on.