New to Glow and ttc had question about chances of pregnancy %

Hello I am new to Glow and have a question about the chance to get pregnant percentage % they gave me. When you first sign in.Does anyone know how they get those figures mine are really low and its a little scary. I didn't know if there was anything I can do to make them higher. Like today im on my period and its at 1% but the highest it goes on my fertile days is 38% which seems extremely low. Can anyone help me figure out what this means and hopefully help me from panicking? I want a baby more than anything so seeing that the highest chance of me getting pregnant is 38% is really scary. Help and advice please!!