Increasing anciety medicine

In November I started taking anxiety medicine, I started on a low dose of 25 mg of Zoloft around Christmas it stopped working so I got it upped to 50. I can tell it's not working anymore but I'm scared to ask for them to increase my dose. I'm so stressed all the time with extra hours at work and all the tasks I have and I know that's making my anxiety worse. I just feel broken that I am not fixed with the lower dose like there's something wrong with me