First day home BF questions!! Help please!!

Ra

My little Elouise was born on Tuesday, tonight is our first night home and it's 3 am and don't have the nurses to turn to. I gave her 1 oz of formula earlier in the day because she hadn't peed and her head was sinking in a bit so I believe she was dehydrated. My milk still hasn't come in and o don't know if I should give her a bit more formula. She hasn't been able to go to sleep. She has been cluster feeding. Should my milk have come in yet? We're starting day 4 now ☹️ also my nipples are soooo sore and look to be getting a bit purple. Her latch was good when the nurses looked, we are workimg on it as she has been sucking on the tip but we're able to do it properly after a few tries, but it's so painful what can I do.

Btw she was c section so I was on an IV and been taking pain meds.