How much milk is too little

I am 3 weeks postpartum and I feel like my milk supply is decreasing. How much milk am I supposed to be producing with each pump session? I can't even build a supply because I'm not making enough. Is there anything I can take to increase my milk supply? I've been eating oatmeal and drinking mothers milk tea. Is there anything else that can help me. Thank you

This was my first morning pump and I got only 7 ounces from both breast combined. It took about 45 mins to a hour to get that