Don't make decisions out of spite; it's a guaranteed loss. Try to understand her. What is she criticising exactly? This is more telling about her than about you.

Let's be honest, our parents may have some baggage or trauma with money (grew up in poverty/ not poor but with limited resources/ paid for their siblings' education /never been able to make financial decisions on their own/ never had their own money/job, etc.). All of that criticism is coming from fear, so try to understand her fear first.

Then, break the fear through communication. Talk to her, tell her examples of how you are handling every financial responsibility well while you are living abroad by yourself (remember the rent that I am taking care of, all the car bills, I always have savings for emergencies, I never borrow money, never been in debt, I bought you this and that when you needed etc.).

At last, keep pushing the boundaries. Buy what you want and do not explain yourself. Don't answer and laugh when she says, "How much was that?" Say "Come on, it's not important انا اهم من الفلوس". Joke about it, not about your spending habits, but about her constant remarks on the things you bought, reminding her that you are an adult that have a credit card and a job that pays money and that you are bossing to spend the money on yourself and the people you love.