Help Me

My baby girl is a week old today and I feel lost. I use both breast and formula and attempt to stay on the every two hours 2ozs but she is not having it. She fuss and cry until I give her more but I feel like I’m hurting her stomach and I just cry. I’m a first time mom and I want to be the best like every other woman I just don’t know what to do... maybe it’s because I’m getting no sleep but ladies help me