Frustrated decreasing supply

So I started breastfeeding strong. But then my nipples became so sore to the point they were cracked and bleeding. So I started to exclusively pump. I noticed I was only getting about 2 oz so I supplemented with formula which was my biggest mistake. In a week my supply plummeted. I wasn't pumping enough. The last few days I started to power pump and pump every time she feeds. Im not increasing. Im decreasing. I went 3 hours in between pump. First time I got almost an ounce and the 2nd time I literally got drops. I'm pumping for 20-40 mins per session. I'm so frustrated. I thought the more you pump the more you make. How long does it take? Any tips? I'm returning to work the first week of July and it feels like it's a losing battle. My daughter is 4 weeks old tomorrow. Is there any hope of increasing at this point in time? Ive tried lactation cookies and body armor as I've heard they help but no success.