Having a hard time producing enough milk

I’m two weeks postpartum surrogate mother and started pumping 3 days ago because i didn’t have a pump. I’ve been trying to get my milk supply up by eating oatmeal, lactation cookies, mothers milk tea, nettle and chamomile tea, body armor drinks, magnesium, black seed oil and nothing seems to be helping. I’m only getting about two ounces all day. And i don’t feel milk coming in unless I pump. Why is that?? Someone please help I need to get my milk supply up