Definitely not normal, but not gonna lie, I can relate to your sentiments. You already realize killing her isn't an option--she is your mother, and that kind of baggage would likely stress you out even more, and even if she makes prison seem more appealing than being around her, I can assure you that it's an absolute hell hole. I would recommend making more attempts to be vocal and communicative with her in a respectful manner. Obviously don't tell her you think about killing her, but just explain that you're trying your best, and her behavior is really stressing you out. Also explain that it upsets you that she takes so much of your money for frivolous products, when you're working very hard for that money and want to save it up for your own future. Beyond that, if things don't improve, just work on maintaining your calm and patience, take a lot of time to yourself when you can, to mentally relax, and realize that you're 17, you've already made it so far, and once you're an adult, you're free. If its an option, I would also recommend seeing a counselor about your emotional distress, school counselors are free and obligated to keep confidentiality, unless they feel you're putting yourself or someone else at risk, so as long as you just explain that your mother is stressing you out to the point that you want to be rid of her--and not explicitly verbalizing any plans at murder, it would help you a lot lol. And if you aren't comfortable with that, even finding a good friend or friends to vent to, can make a world of a difference. Hang in there and don't forget to breathe.
personal experience/similar circumstances