As a young professional woman, it probably feels demeaning to be openly criticized. To have a manager repeatedly do that is disrespectful and tells me a great deal about her leadership style or lack thereof. Finding errors and correcting work isn’t helpful when coaching behaviors are absent. Let's look at the situation from multiple angles.
You say things changed when she became your boss. That’s not unusual in and of itself. Have you given thought to why things changed? Or, when? Did it change gradually or was there a particular incident? If an event triggered this change, openly addressing that could be helpful. You mention age. You may be right. When I was younger, my social life often got in the way of my job. I came in late, was always on the phone, and I didn’t understand boundaries when sharing details about my personal life (think Hannah Horvath in Girls). How well do you interact with others in the office? There may be dynamics fueling the fire, so consider that for a moment if you will.
Next, think about the quality of your work. You are learning new tasks so you may have skill gaps. Could you benefit from additional on-the-job training? At a minimum, you may need to document internal processes and create detailed job aids for reference. Is her criticism and correction of your work a matter of her expectations being unclear or that her expectations change? It may help to discuss the task to be clear on what success looks like before you start the work and take notes! Read my post Off track? How to exceed your boss' expectations. We all make mistakes from time to time. Stop and assess how often and why you make them. Are you distracted, tired, stressed out, or bored? Once you see things objectively, you'll know what part in all of this you can own (if any) and rectify.
After assessing the situation, speak to your manager if and when you are ready to do so. Be prepared with talking points like 1. You feel she’s unhappy with your work, and you want to talk about what you can do differently. 2. You have become increasingly frustrated by not meeting her expectations and you want to work together to change that dynamic. 3. Ask her what she considers the primary issues and how you might resolve them. 4. Share what you can do differently/what you own to show you're committed. 5. Be prepared to share how her behavior makes you feel and how it impacts your performance if the discussion is open and honest and you feel she will be receptive to it AT THE TIME, otherwise, stay silent on this point.
Bottom line: She may or may not recognize her behavior. She may or may not care. She may or may not admit her part in the dynamic. Even if she doesn't, you may notice a change in the days that follow. If the discussion doesn't go well, or you see no change in her behavior it may be time to start looking for a new job. You deserve better.
Best of luck to you!