Sudden drop in milk supply :( help

My LO is now 4.5 months. I used to pump 34-36oz per day but starting from this Monday my milk supply decreased by almost 50%. I am short at least 2 bottles everyday now. I bought formula but don’t want to give up. I am so sad that I won’t be able to feed my LO. I tried drink more water and mother milk tea, lactation supplement and oatmeal for breakfast but no luck. I heard that power pumping may bring back the supply, does anyone try this method and does it works? Thank you so much in advance :)

“Mama is not able to feed me”